Yeah sound-wise Pete is probably the least important member of the core trio.
Back problems are no joke, though. I would not wish that stuff upon anyone.
I'd have to disagree if you're referring to the actual sound of the percussion: a quick listen through Morbid's discography suggests an attitude toward production that's much more flexible and gutsy than most other U.S. DM outfits. No two Morbid Angel albums sound at all alike production wise.
But in terms of performance it's pretty straight forward. I don't think Pete has contributed an artistic voice since the C album, and that was incidentally the band's last legendary release. Formulas is a solid listen - it also renders Nile irrelevant - and Gateways features some great drum patterns that the production values slaughtered for the most part.
The bonus disk on Heretic explicitly laid out what role Trey plays in the arrangement of percussion these days. I hope he doesn't go with the drum-machine sound this time around, but if their live show is any indication that's what'll happen. It's too bad: an amazingly accurate rhythm guitarist surrounded by bass-end talent prefers clicky drums while he chugs along. The result has been inappropriately sloppy thus far.