Keeping in mind I've only had the line to test for less than 2 weeks, I've tried to run it through a variety of situations to get an idea of just what it's pluses and minuses are. The spool that was supplied to me was of 4# test, so that somewhat limited me to what presentations I could try. It's also not the best time of year for finesse work on the local lakes. That said, I have been able to get out and toss drop shot and split shot rigs for bass with it, along with a little bit of sissy jig work (caught about 17-20 bass in total). I also got in several hours worth of crappie fishing using jigs ("OTC" methodology) that accounted for another 100+ fish. So here goes:
The lab: I first took the line into the lab and popped it under a high powered microscope. While I didn't have the capability to do a cross sectional analysis, I can tell you that this line does have a fairly round shape as claimed, much more so than Fireline. Their picture on the package gives the appearance of a solid bundle of fibers that comprise a single round filament, but my impression was that it is more like bamboo (if that makes any sense). Bamboo while round, is actually hollow on the inside and has that 'segmenty' look to it. NanoFil appears similarly under the microscope. Two things give me this impression. The first is its shape when looking at knots tied in the line while under the scope, and the second being that I was able to completely flatten out a segment that was creased with a small lab tool. Still, it does a pretty good job of holding that roundness under a variety of situations, which is a positive in my book.
Line Strength: On a straight line pull with just a length of line between your hands, it has really good strength. I found someone else who mentioned they tested it's breaking strength at about 2x labeled strength, and I would agree with that assessment. This is very similar to both Fireline and PowerPro, Fireline also being a Dyneema-based line.
Coating: If you look at both Fireline and PowerPro under a microscope, you'll notice that both appear to have some type of coating on the line, probably as some type of protectant. This also makes those lines somewhat stiff, at least originally until broken in a bit. I didn't really notice anything similar with the NanoFil. That said, after using it for the past couple weeks, it almost seems like it's covered in Teflon (half joking). This stuff is incredibly slick and very hard to get a good grasp on. Regular knots won't hold with this line. I tried both a clinch as well as an improved clinch and both slipped easily under pressure. It did seem like a Palomar would hold, and their recommended 'NanoFil knot', which is actually a double Palomar might be good reassurance (more on knots later).
Diameter: As claimed, this line is incredibly thin. As per my intial post about 10 days ago, my 4# sample of NanoFil had a diameter that was .001" less than 2.5# fluorocarbon. Doesn't sound like much but it makes a difference. I found several eyelets on jigs that didn't seem to have an open gap where the eye was formed, but the NanoFil would slide right out. It's something you'll want to be aware of when using this line. It might take an extra crimp with your pliers to get some of your eyes on certain baits to close down enough to not let this happen.
Knot strength: Here's the first weakness I think I've found with this line. It takes much less pressure to break the line once a knot has been tied in it versus the strength of the line itself. While you have to work a little to get the 4# straight segment to snap in your hands, it is pretty easy to pop the line once it's tied to a bait and get it to break. I'm guessing that if tested it would probably rate right around its stated breaking strength. It's something you'll want to keep in mind.
Ironically, this actually turned out to be a good thing when crappie fishing. When you hang a crappie jig in some deep wood and have to break it off, it's not uncommon when using other lines, especially mono and fluoro, for the line to "break high". In other words, due to good knot strength, sometimes the weakest point in the line might be a crease or nick 10' or 20' up the line. As such, when you break off, you leave a lot of line in the water attached to your bait, and lose a lot of line off your spool. I broke a lot of jigs off in hung timber when crappie testing, and can never once remember where the line didn't break right at the knot, saving nearly the entire length of my line. So it's not all bad in this regard.
Casting Distance: Another major claim of this line is that it casts farther than your normal lines - I agree. You can wing this line a long way. Simple little flips will get you out more than you need in many situations, and good heaves will throw a small bait a good distance. One evening a bunch of little fish started rising and breaking the surface all around me. Couldn't tell what they were, but I guessed either little crappie or white bass. This was an evening I was split shot rigging, so all I had was a 4.5" worm, a tiny split shot hook and the lead. I removed the lead, bit the tail of the worm off to less than an inch, and threaded it on the split shot hook. Amazingly, I was able to cast that little 1 inch weightless worm tail 30'-40', and managed to confirm my suspicions. Believe it when they say this line casts well.
Sensitivity: Being a superline, you would expect great sensitivity under tension, and this is what you get. No problem feeling everything my little split shot banged into when drug across the bottom. Same goes for bites. What surprised me a bit was the apparent sensitivity when crappie fishing under a semi taut line. Fluorocarbon usually excels here, and mono is so-so. Most superlines don't do well because of their density. They're light and "flighty" in air. NanoFil acted much more like a mono or fluoro in this category, and I was pleasantly surprised with the results.
Density: I saw someone ask online if NanoFil floated. The answer is yes. Being comprised of Dyneema, it has a density that is lighter than that of water. I put a segment of NanoFil and a segment of Fireline in a tub of water and repeatedly pressed both under the surface. In both cases the line segments would repeatedly rise back to the surface. I noticed the same thing when crappie fishing while letting my jig sink, the line laying on the surface only to be pulled under the water toward the end of the line as the jig sank deeper.
Knots: I mentioned about what seems to be poor knot strength, and what knot Berkley recommends (NanoFil). I did play around with a few others and if given the time, I would personally recommend a double line 5 turn uni knot. You can Google search this site or the Internet for instructions on how to tie it. Not the fastest knot in the world to tie if you're in a hurry, but I believe it is a bit stronger knot to use with this line. It's what I now tie with this line if I'm in a position where I have the time to do it right.
Lilne Color: This line has an obvious bright white color to it on the spool. While I've never owned any Fireline Crystal, I think that is probably the closest thing in terms of line color to compare to. Interestingly, the white shows up pretty good in terms of line watching, much better than red, green or smoke superlines. The hardest situation to see the line under is an overcast but ripply day with glints of sunlight reflecting off every wave. The line blends right in in that case. But on bright sunny days or flat calm waters, the line shows up pretty well and is easy to follow.
Current thoughts - bass: Just like I think 4# Fireline is a little too light for bass fishing (think sissy jigs), I think that 4# NanoFil would be a bit risky also. I'd like to get my hands on some 6#-8# test and give that a try. For drop shotting I simply added a leader of 6# fluoro to the NanoFil and then tied my Palomar as usual. This is also an option if you're concerned about knot strenth or line visibility. I'd need to test leader connecting knots a bit more to see what worked best, but you might get the best of both worlds going this way.
Another option is to use this light of line with a more moderate action rod, something that will provide a bit of cushion and impact absorption. This will work for some tactics, but not with others. I definitely plan on picking up at least one spool in these higher tests to play with when the sissy jig bite comes around again.
Current thoughts - crappie: I need a bit more time with the line to be certain, but as of right now this might become my "go to" line when crappie fishing. Sensitivity is great, casting is unreal, and the line handles better than most any other superline I've used. It's thin diameter cuts through both the water and the wind, and the line doesn't seem to be as "flighty" as most superlines. It really does seem to act more like a mono/fluoro than a braid in that respect.
One of the biggest issues for me with crappie fishing is there is no perfect line. A lot of bites are detected by line watching, which is easy with a fluorescent blue mono or yellow superline, but terrible with a fluorocarbon no matter how they try and tint it. I think I can live with the white NanoFil color in most situations though. Fluorocarbon gives the best slack line sensitivity of the bunch. Back on the negative side though, monos and fluoros both stretch a lot, so hook setting with a lot of line out or in really deep water can be an issue.
Then there are the handling issues. Mono twists a lot and can jump off a spool if wound on wrong. Fluoro is fine in lighter tests on a spinning outfit, but suffers the same twisting and jumping ability. Superlines handle twist great and tend to relax nicely, but their coatings can sometimes make the line not as user friendly as it could be. There are lots of other little things I could get into, but if Berkley ever figures out how to make NanoFil in 'flame green', I might have to give up bass fishing :)
So final thoughts - Berkley might really have a good thing going here with this NanoFil. I want to pick up a couple heavier versions of the line to play with things like sissy jigs and floating worms, as well as drop shots, etc. for bass fishing. On the crappie side, more testing is needed, but the difference between the two outfits I had with me today (one Fireline, one NanoFil), for the way I like to fish, was night and day. I can't wait to get out and try it again, head to head against my crappie mentor to see if it's as good as I think. Berkley - please make this line in flame green next!!!
NOTE: See the following updated site review after 6 months of on-the-water use: 6 month NanoFil update