I know these were not your original choices, but 2 of the most praised dropaway rests are the Trophy Taker Shakey Hunter and the Muzzy Zero Effect.

I've tried the Trophy Taker and I loved it. I now shoot a quicktune 4000 dropaway, but I have very few shots out of it and can not comment on its effectiveness. I have heard great things about the dropzone.

Good luck and welcome to the boards