I could only guess that you might pick up anywhere from 1-3 fps, but again, that's a guess. As far as accuracy goes, a whisker biscuit is capable of being just as accurate as most common rests used by the bowhunting community, I think. I've never used one, but its certainly got a very big fan base.

I've also never used the two dropaways you've mentioned. I prefer the Muzzy Zero Effect when I can use it, and if unable to use that I'll go with Vapor Trails Limbdriver.