I put 780 on the HT which I got cut down to 750. Got 780 on the bouncer but gonna cut them down to 750 or 760...not decided yet but I don't think you need anything wider unless you're really wide shouldered.
When you put them on they'll feel strange at start of first ride but at the end of it you won't go back.
Went from a 720 back to 690 as I couldn't get to grips with the wide'uns but have recently fitted some Renthal Lite 740's and have to say I'm really starting to like them as I quite like the feel. They were also very helpful in strapping a single man tent to it btw, wouldn't have managed that on the 690's as there wouldn't have been any room to reach for the brakes