Hey Brian -
Just saw your post. I guided and safety kayaked the Gauley in the mid- 90's through early-00's. I'm still involved in the industry and with river recreation. Please check out the articles below. I wrote the one for Paddler Magazine and Mark, who wrote the one for National Geographic, is a friend of mine. You and your buddies will probably enjoy these if nothing else.
Advice - I would say don't worry too much. With enthusiasm and a bit of fitness you guys will have a great time on the Gauley with Ace. There are several great companies who run the Gauley; and they're one of them. I've paddled about the globe, and I still consider the Upper Gauley one of the greatest day trips in the world. The rapids are really big and fun with generally little consequence (Class V-ish drops with Class III-ish consequence, in general,) which makes the place the mecca that it is. On top of that, the water is relatively warm. Take some polypro/capilene and whatever splash tops/pants you have and you'll likely be overdressed for late September in WV. (That said, it might snow on you!!!)
I'd say, for the best trip possible, get in as best shape as you can, talk to the river manager at Ace when you arrive and tell him that you guys want a helluva ride, and he'll set you up the the best guide that he can that day - if you look like you're indeed gung ho and in shape. You might even consider upgrading to the extreme trip - I'm not sure what Ace calls it, but most of the companies offer a wilder trip in smaller rafts where they take looser lines.
Anyway, enjoy. I hope this helps. Articles:
Paddler Magazine Online : Gauley Daze!
What Makes West Virginia's Gauley Rafting's Madcap Mecca?