I have been frustrated with the quality and price of fluorocarbon for ages. I used to use YGA's Mamba originally and found it very reliable, although a little thick versus BS and dabbled occasionally with the more expensive brands but often found them brittle and unreliable.
The last two years, I have been using Orvis Mirage which is very good but expensive and hard to find in 100 mts spools and Riverge which is equally expensive and still gives me the odd unexplained breakage.
A few months ago, amongst all his tackle sourcing activities, Ben came across Asso, which is an Italian brand but I think is actually manufactured in Japan. Being a fellow Hanningfield regular he brought me down a couple of spools to try out when I was practising for one of the National Eliminators there - 0.23 and 0.21.
I always buy leader material by diameter not BS as that is what affects presentation and BS is usually, well BS (but of a different kind

. Depending on knots, stretch in fly line, style of fishing, etc fluoros tend to break against all sorts of strains in my experience.
Over the couple of months I have had it, I have used the 0.21 primarily for nymphing and the 0.23 for pulling, most usually on heavy Sixth Sense lines and I have been extraordinarily pleased - so much so that I kept badgering Ben to stock it !
I cannot think of a single break in that period, using Asso, and I have had some good fishing often in very windy conditions on Hanningfield, Grafham, Brenig, Eyebrook and other venues.
I have been fortunate enough to qualify for some of the major finals coming up and, although I still have both Riverge and Mirage in my bag, I will be using Asso, in preference.
Great name too, think of the one liners
Charlie