We can support it, but we don't allow it because of the heavy resource usage that it causes. It's a nice looking forum for sure, but it's coding is terribly inefficient, which causes a lot of problems in a shared hosting environment.

We do support pretty much every forum available. YABB and Ikonboard are the only ones we restrict. We have one touch installs for XMB, PHPBB, and Invisionboard. Here are some links to some conversion scripts:

For PHPBB:

http://www.phpbb.com/downloads.php#converters

For XMB:

There are none that I'm aware of. (support for XMB isn't the greatest from their community)

For InvisionBoard:

http://www.invisionboard.com/?resources

This way, you should be able to convert to something faster and more efficient without losing your existing database. :)