I've tried em and they are pretty nice, but I went with a buss cable anchored drop away rest for the simple reason that in a pinch, I can temporarily fix it if I had a problem in the woods. If one of those NAP rests were to fail or break(Murphy's Law, and of course it would happen when the 180 class walks by)you're up poop creek without a roll of T.P.. Now I'm not saying it's not a good rest, I'm just saying I'd rather go with something I can re-rig or fix in a hurry. Truthfully speaking the safest way to go is a few-piece-construction "traditional" rest for reliability, but if you want the shooter friendly benefits of a drop away rest I'd go with a buss cable anchored system. My buck O' two.
If it's brown, it's down
Rog