I'm thinking of installing Windows7 RC. I'm wondering if the auto-updates along with a production licencense will be sufficient to convert the RC to the RTM. Or will I have to reinstall?
Windows 7 RC will expire June 2010. So you will be able to continue to use it until then. You may be able to upgrade it to the full version, but most likely they will recommend a fresh install.
They recommended a reinstall when moving from the Beta to the RC, but they provided a work around. Most likely they will provide a work around at RTM, if not you can probably find a way.
Additionally, nothing beats that fresh installed OS feeling. Reinstalling after 12 months of use is probably a good plan anyway.
Based on the release blog, you will need to reinstall.