Just going back to this point:

"and yes it's possible to use the same directories, however during yoru import you'd want to use a new directory, then change the directory name once it's installed."

So I can install the new forums in

/thisfolder

and then when it is all setup just simply change the name of the folder to

/thatfolder

Simple as that?

And when I import, does my classic need to be closed?

Thanks for all the help!