My decision whether to get the III right away has bounced around like a ping-pong ball in a clothes dryer. I'm super happy with my XL+/MFC rig, and know it'll do everything I'll ever need it to do as a guy who just plays one or a few local pub gigs per month. On the other hand, the new possibilities with the III, including the new FC12 and the fact that it's the future path of firmware and feature updates, keeps calling to me and saying "Buy Me!"
If I sell my MkII, my XL+, and my MFC, it'd take a lot of the sting out of buying the latest and greatest, but I would need to put together the cash to buy the new rig before selling the XL+ and MFC, since I rely on them for gigging. Looking at other things to sell, too. Anybody need a wife? She can't cook, but she's pretty low mileage, lol.