I dunno about this versus revvies and all that nonsense, but this loader, in ideal conditions, will feed 13bps. performance drops off around 20 balls, and over 200 balls. Keep the hopper happy, and it will treat you pretty well. I got it in a color to match my gun, a plus, in my book...survived a hopper hit. Good carrying capacity.
Esprit at 13bps can outshoot it if I don't conciously stay vertical, but that's gravity, not the hopper. Super stable guns won't give enough backshock to activate the hopper. it can be loud, but no enough to give away your position...if they can hear it, you should *already* be lighting them up.
I'll give it an 8...an sure upgrade over gravity, and from everyhing I've read and seen, comparable to a revvy. If you want to make sure that your gun feeds on full auto, you have to pony up for an Evolution2 or a halo.