I have personally installed all of the leaked versions and I can tell you there is no new features in any of them. It is unlikely we will see any new features or UI changes to 7 at this point in development, and new builds only contain minor bug fixes.
It is my advice that you stay with the RC (7100) as it is rock solid and is the only supported release from Microsoft.
If the RC is going well for you, it is in your best interest to stay with it. I have it running as my main OS as it is the only build that supports PunkBuster.