When you get ready to dump the Vista, it would be interesting to see how an in-place Win7 Upgrade done on Vista compares to the one you did on RC.
You could compare the two for the 30 days your activation counted down on the Vista upgrade, then switch your final activation to upgraded Vista if it is a better install.
I ran RTM upgrade from RC side by side with clean installed RTM for a month and the clean install was snappier by comparison.
The 7 RTM was a great improvement over RC, much snappier without the monitoring software. I wouldn't settle for any less than that, and certainly no hangs ever!