I recently tried out one of Berkley's variations of fireline, the Ultra 8 Superline. I have mixed feelings about it, and I'm curious to see what others think about it as well.
I tried both 10lb on a spinning reel, and 30lb on a baitcaster. My experience with braided lines is mainly with 10lb (spinning) and 50lb (baitcaster). They are of similar diameter, so that is what I am comparing the lines to.
Bad news first, I was not a fan of the 30lb. I used it for a hollow body frog and a large walking bait, which is what I do with 90% of the heavy braid I fish. The first dislike I had was for the stiffness of the line. The line has memory, and would lie on the water in small coils on a slack line. This means when you are working a bait, each movement of the rod tip is suppressed by the coils, which sort of act as a shock absorber. The coils of line straighten as the line tightens, so if you give the rod a sharp twitch (like when walking a frog), the movement of the bait is "smoothed out". This also makes pausing the bait difficult, because the coils re-form when you stop the rod movements, causing the bait to glide forward slightly. Having the bait come to a dead stop during a pause on the retrieve is often critical for triggering strikes.
My other dislike with the 30lb braid was the diameter. I don't have the tools to measure it, but the package says it is .38mm. This is slightly larger than many 50lb braids on the market which come in at .36mm (what I have used for the same applications prior to this). My best assumption is that the roundness and coating used on the line makes it seem even larger than that, because it seems much bigger than standard 50lb braid. I don't know why you would want a lower pound test line with a higher diameter, especially on a baitcaster, when you can nearly empty a spool of large diameter braid with a heavy bait on a long cast. The combination of the large diameter and springy/stiff nature of the line made it difficult to make long casts with a baitcaster, due to what felt like friction on the guides (this also could have been from coils passing through the guides). I could still make reasonably far casts, but not as far as what I can do with most 50lb braid. Extra long casts are common for my uses of heavy braid, either reaching schooling fish with a walking bait, or reaching a spot far back in vegetation with a frog, where it may be too thick or too shallow to maneuver a boat closer.
The 10lb Fireline Ultra 8 was much better for me. I fished it on a 2500 sized spinning reel with a 7' medium action rod. I used it for fishing a weightless worm around lily pads. This would test the strength of the line well, because often times the strength of the line doesn't get tested well due to the nature of spinning tackle fishing. I attached a 14lb mono leader to the braid, because I use a leader 100% of the time with braid on spinning gear, and wanted to test the knot strength of the braid. The roundness and coating on this braid that was detrimental to its use on a baitcaster, seemed to help in use on a spinning reel. I was impressed with the casting range I had even with a 6" worm and no weight. It also cut through the lily pads well, not that you typically do that with spinning gear, but it did work! The line was still a little stiff, I assume the coating is responsible for that, but since the line is much smaller in diameter, it wasn't nearly as noticeable.
My opinion on Berkley Fireline Ultra 8 would be that it is good for use on spinning reels with the smaller diameter braids (14lb, 10lb, 8lb, 6lb, and 4lb). I would bet that the coating sheds water well, which would make it an ideal line for fishing when temperatures are below freezing, keeping water off of the guides and reel, as well as not freezing solid by absorbing water (which other braided lines have done in my experience).
If you've used this line, let's hear what you thought of it too!