Just to re-iterate some of the comments above, you MUST do a fresh install to RC if you are using any previous version, including the internal testing early March builds that some people have taken it upon themselves to install.
While it might appear that upgrading from a previous version “works” without apparent problems (and even reports the correct release version) some system packages will be out of date and will be unable to update in the future, causing you to have a mixture of old and new packages.
Also, some files which are preloaded in the image (and not part of any package) will not be present and correct. These will both cause you problems down the line, and cause a support burden for us trying to figure out if a particular problem a user is having is due to a genuine bug or because you have tried to upgrade a pre-RC release.
So please everyone, we mean what we say when we insist that you do do a fresh install to RC. If you have invested a lot of time setting up Kodi then it is usually ok (although still not recommended) to backup and restore your kodi folder located at /home/osmc/.kodi/ however if you have not done much configuration starting over is probably best to be on the safe side.
There will be no major changes or restructuring between RC and Final like there was between Alpha 4 and RC, only obvious bug fixes and last minute tweaks, so we will do everything in our power to ensure a smooth upgrade from RC to Final release, and we will be testing that upgrade process carefully before releasing it.
So those of you waiting to set up complicated configurations who might be worried about having to reinstall again can relax - upgrade from RC to Final (and beyond) should be a smooth process with no need to re-install.
We have invested a lot of time and effort to get our packaging system and upgrade process as solid and robust as possible. We think you’ll like the improvement in the upgrade system over Raspbmc. 