I have been using Fireline for over two years on my floating line long leader set up for the back bays and soft surf. This past year I have also used it on Streamer fishing. No stretch, sensitivity and thin diameter is what I was looking for to build a leader for the surf. A 10' intermediate sink polyleader followed by 8' Flor/Braid leader extension. The extension set up is 12" of 12LB, 5' of 4LB dia fireline (10LB test), 2' of 8 to 10LB final tippet. I use to use up to 20' total off the fly line but with the thinner extension the fly has no problem in sinking to the bottom. Thicker line sinks slower and will have a tendency to be pushed around by currents. The thinner leader just cuts through the water twice as fast. There is no question that the braided line with it's no stretch is far more sensitive than anything on the market. Even with the 4LB that I use it's remarkable how much more one feels. I have tried different brands of braid and I'm sticking with Fireline. As for Streamer fishing only two words are needed "instant hookup". Jarring strikes that no hook sets are needed. All my knot that I connect flor to braid are tied with the Crazy Alberto knot. I just find this knot easier to tie for me. Does anyone use braided line for any application in fly fishing?