I think I want to try another forum software. How can I export my forum to phpBB, vB or IPB?
By asking those who work with phpBB, vB or IPB
There is no standard interchange format between forums. They all have to provide their custom import tool and have to support other boards. You better do a good analysis on what you need and test the software you have in mind before you do the switch. Otherwise you would have the export/import effort soon again.