Tough decision. We have a lot of local loggers running the 7900's with success. Known problems are: weak av mounts, fuel tanks become brittle in the cold and the HD filters come unglued. The filter problem is what killed Mingo's saw. My 7900's are super strong runners and have held up fine so far, but in limited use. My one 7900 has so much torque, I don't think I ever pushed on a stock saw so hard to stop it. Very impressive. I do prefer the feel of the 372 though.
Huskies still dominate the market around here. I love the feel of the 372 (own 3 of them right now), but can't get used to the extra weight of the 575/576 (own 3 of them right now). I don't own either an XT or XPW, so I can't comment on those models, but the old 50mm 372's get the job done well and you have obviously had success with yours.
BTW, I thought the XPW and XT had little to no power gain over the regular 372? I swear I've read that in the past. So what is the deal? Do the XPW and XT have noticeably more power?