I have done this particular upgrade a couple times without incident, so it worked for me, except...
One time I ended up with a problem, as I was asked to upgrade a site, and no one told me that they had made some Ditto changes before.
Fortunately, I had backed up the files first. All files! I would recommend this, as when you’re working on lots of sites, who can remember everything?
I can troubleshoot quickly, so I was able to isolate the problem rather than simply reloading all the old code, which could have been messy.
good luck!
D
Edit: I spoke a little too soon... I did update to 1.02 from 0.963, but not the "RC", or release candidate. The same principles should apply, though.