I run multiple sites, always have. Have tried vBulletin, and phpBB. It wasn't until I tried SMF that I decided I would never use the past two again.
Simple Machines Forum has served me better, by far, than vBulletin or phpBB. SMF has a conversion file on their site. if there is a test site for this one, may I suggest giving it a shot?
And the TinyPortal portal, is awesome for giving your site the multiple pages aside from just forums.