I've had the QT4000, Trapdoor, TT Shakey, and DropZone. I'm currently using the DropZone and have been very happy with it. Some have said it is loud, but I don't hear it. Maybe I got lucky with a quiet one, but compared to the TT it is a whisper. The Trapdoor leaves a lot to be desired. The QT4000 is a great rest but not enough adjustment. I most likely will not switch from the DropZone any time soon.