I used this stuff years ago w/ gut crosses & loved it. Originally, they sold it as Extreme Spin 19, which was a full pack of the 19g Kevlar. I bought all the remaining packages (seriously) back in the early 2000s when I found out they had discontinued it.
I've since moved away from it, but there is one person I string for who uses it in the mains w/ gut crosses. I still have 2 more packs remaining, good for 4 string jobs, then I'm going to have to give him the bad news...
"Nobody beats Vitas Gerulaitis 17 times in a row" -- Vitas Gerulaitis, after beating Jimmy Connors on his 17th try.