Using vBulletin 3.5.x uninstallation and upgrading is no problem and can easily be done using the Product-Management of vBulletin
For vBulletin 3.0.x there will be an uninstaller.php included
For Upgrades from v3arcade and "old" ibProArcade I must have a look on their DB-structure to do any converter - I would really be happy if anyone of you could make those two converters so I can include them in the Release, of course the author of the converters will instantly get the current development-version of ibProArcade and get named in the Release