If you are still skeptical about trying out Firefox 2 RC2 then maybe you should tinker around with the portable version that has been put together by John Haller. It includes his awesome new launcher that offers significant speed improvements when re-launching Firefox from the same computer.
If you are experiencing issues with incompatible extensions then you should either disable the compatibility check or use the Nightly Tester Tools. Those two methods will allow you to use your Firefox extensions but that doesn’t mean they will work. A lot of the extension developers appear to be releasing Firefox 2 compatibility updates including Google who just released a new version of their Notebook extension.