All the bug fixes from the RC to the RTM will obviously be included. Either way, you'll still have to buy it at some point... so it's up to you if you want to buy it now or wait until the RC expires.
+1. Personally, I would buy it now if you can afford to, so you don't have to worry about it later. You still have 3 months before it will start rebooting every 2 hours automatically, and 6 months before it stops working completely.