I've been running it now on a machine with RC2, build 5744 installed for about two weeks, trouble free.
Shame that the same can't be said about the disc drive. It recognises a disc has been inserted, then asks to either insert a valid disc or even just a disc, (hang on, haven't you just switched to saying DVD-ROM inserted). So unless this is machine specific, which is almost a certainty, I'd import everything before upgrading or do all your importing on a different machine. My preference for such a machine, a Mac.