I said most of this over on the M&F forum, but there are tools for account mergers, even tools for forum mergers, but there are particular requirements for most of them: forums must be running on the same [logical] server, tools require some trial and error to get the process to run right.
Most of it comes down to requiring some understanding of php and databases, and the time to do it all. It will almost invariably involve taking the forums down for at least a few hours to ensure everything works right.
The bigger issue is what the new forum layout will be. This forum is already pretty bloated as far as sub-forums go, with entire categories that haven't seen use in years, and forums and forum locations that don't make sense when you've got two different major titles that the board is servicing.
