If we're talking about an unmodified beta upgrade, wouldn't it be easier to just dump the database table structures from the two versions for member and content-related tables, compare those and note down queries for synchronizing the two, and just wholesale replace everything else?

Please be aware though, if you use a third-party upgrade script/procedure for upgrading a beta, or from beta to RC, all your future bug reports will be under suspicion. Those who do this should keep a separate clean see more latest beta install to check if their bugs can be duplicated there, if they intend to report them in.

Also, if the custom upgrade attempt is only partially successful (which may not be immediately evident), chances are your site may go to hell when it's time for the next upgrade and you're using a Boonex-provided upgrade script.

I don't mean to be a party pooper, but these are issues people need to take into account. Kudos for the effort, mydatery.