Ok, so my 7620 arrived this morning (lame pic below, will post better ones tomorrow), setup like dogsh*t with an ancient, corroded set of 9's and a 52 on the bottom. The previous owner hadn't even bothered correcting the trem angle - the string tension was so low the lo-pro was sitting right back in the cavity.
Anyway, ripped those nasty, tetanus inducing wires off, cleaned the 8 year's worth of other people's skin off the fretboard, installed some D'Addario 10 - 56's, set the whole thing up and voila. Plays great now. Medium-low action, no buzzing.
Two major gripes
a) The pickups sound like crap. The neck is actually a Duncan Designed, NOT a Duncan JB as stated by the seller. That's coming out ASAP. The Blaze sounds ok on the top 5 strings, but the bottom E and B sound awful. Whatever the opposite of clarity and definition is, that's what it sounds like. Seems quite low output as well, along with the nice crackly pots and switch. New pups and a rewire methinks.
b) Even with a 56 for the low B it still feels like a rubber band and sounds like it wants to be tuned at least a full step higher. What d'you reckon? Replace it with a 60? 62? My local shop didn't have anything bigger than a 56. They did have a Marshall Mode Four half stack though, which I played a PRS through. Wow. *Adds to GAS list*