I wouldn't know about adults since I only have a juvenile, and she's my first.
As for her missing and biting you? Not likely to happen with tongs/forceps.
http://www.amazon.com/RecoAquaRep-Qu...+feeding+tongs
The ones I have are actually shorter than this (and I only just realized looking back at my video that I juuust had the tongs out of frame) but this shows you how far your hand will be from the actual rat. I do read on here occasionally about people who dangle the feeder with their hand and end up getting tagged when the snake misses. But I doubt it's possible for the snake to miss that badly with all that distance between the feeder and your hand.