I dropped about 50* on the highway and probably 150-200* on the top at full-throttle. Not a huge amount, but it does help.
I bought mine (a Haisley) because it was priced right (about $400) and I just happened to be there getting my fire rings cut. Van did show me the numbers of the various cams on the market at the time, and his was one of the more aggressive ones that you could fit before having to cut the pistons. So far I'm happy with it. But it is a regrind, which gives some folks concern about durability. I've been running it for a few years now and haven't seen much change in my valve adjustment, so I suppose it's hanging in there.
If I were to do it again, I'd probably try the F1 Helix 2. Folks have been happy with them, they're not regrinds, and they're priced right. I think they can be had for around $500.