Hi Shaggy.
I vote for option 1. I think keeping two separate forums only confuses new Expy owners. After I bought my Expy last week I googled for a forum and came across both EF and FEF, and didn't really know which is better. So I ended up registering on EF and then noticed that ppl had migrated to FEF months ago lol.
Did you take a look at the ImpEx option in VBulletin?
https://www.vbulletin.com/docs/html/impex
This is what i'd do:
1.rearrange the sections on EF to look just like FEF.
2.make a backup of the FEF database.
3.make a backup of the EF database.
4.use the ImpEx feature to import the FEF backup into the live EF database.
5.if the import doesn't work, revert EF to the backup db and start copy/pasting important threads manually. I bet many users would be glad to help out. I sure will.
BTW: I hope you plan on keeping both domain names, even after you take this forum down, right? It would be nice to have both domain names point to the same forum.
my 0.02