For a start, remove the MOVIN ON UP banner.
Postpone any plan to 'migrate' people to the beta at this time and make it clear that you have.
Go back and at least make sure all the current comments-handling functionality is in place on the new site before even thinking of trying it again. Run a story on the current site about the beta again when you have done that, and see how it's received in the comments [you know - the thing Slashdot excels at] before switching people over to it.
Then again, the above only matters if you're concerned about keeping the current user base. That's open to question.