A Release Candidate (RC for short) is late-beta, pre-release version. It is generally more stable than early beta versions.

If no one submits any bug reports or pressing suggestions, this will be the version that will be released to the general public via the "There is a later version of..." menu that you get when you wear your toy.

You should try the Release Candidate because it has the latest fixes, new features and improvements, and is rather stable.

Don't forget to IM Lulu with any bug reports (don't assume someone else has done it).