Why not just use good ole' phpbb?
I've used them for about 4 or 5 years now. Never had a problem with them. They also have a very nice point/shop feature.
I also agree with whoever said that if its not broken, don't mess with it. I currently run phpbb2.0.17 and on the 31st .18 came out with some upgrades. Well, thats all fine and dandy but I have over 30 mods installed on our bored, some very big ones that will be hard to redo again. So, I'm just sticking with .17. Maybe when Olympus comes out...
Don't convert though, that'll be a pain for you guys.