If you have the funds i would say upgrade.
Vb is far better plus members seem to prefer it.

I'm growing to quite like vbulletin but their having a laugh with the pricing!
I'd love to get my hands on a copy of vbulletin just to make some decent themes for it! but I'd probably never use it as a forum script - much like most others!.

The Vb folks let you have multiple installs from the same license key, just as long as only one forum is actually turned on.

Ask someone nicely and install a copy with their key, turn the Board Offline and you're set

Wow that's pretty good that you can run various test installs with VB with still running your main board via the same licence!!