I'm not sure what all transfers exactly, I can setup new ones for testing and leave these here, see if we like them. If we like them then we can really move; I am new to SMF too.
I want to avoid confusion between multiple forums as much as possible, so in the interest of that, lets keep any trial period short and relatively quiet (see steps below). I wouldn't want any period of time where real posts might be showing up on a test/obsolete forum that won't last. I'd suggest the following process if it's not too much trouble (my many thanks to you for your efforts):
1) Trial transfer -- try copying the data over to the new forums without affecting the existing forums. Try it out locally and make sure things look functional. Maybe I could take a look too, but don't make them too public because we don't want to risk regular members posting in the test forum and losing their posts or anything like that. (Perhaps a link to the new forums buried in this thread would be "private" enough as long as its clear that the new forums are not live yet.)
2) Set a date when the forums will be migrated and let us know to allow a chance for regular visitors to be aware that the forums may be unavailable for a short while
3) "Take down" the current forums to avoid new posts getting lost in the process of transferring live data. (If possible put a "temporarily unavailable" message up at this address.)
4) Re-transfer current data from the current forums to the new forums.
5) Bring the new forums online at the same address as the old forums. Bye bye old forums.
If transferring data twice is too much of a pain, maybe we can arrange a time to be online at the same time so I can get a quick look at the new forums (at a temporary/private address?) while the old forums are offline to determine whether to go ahead and bring the new ones online or to back up and reconsider.