At least it narrows your research down to 3 check out their official threads here on rctech and you'll get a great idea of what each can do. I thought the 4pv had its own official thread but it seems I can't find it.

http://www.rctech.net/forum/radio-el...anwa-mt4s.html

http://www.rctech.net/forum/radio-el...io-system.html