Ridiculous to delete forum content to 'upgrade' software. A forum is it's content, no use without the content regardless of how pretty it looks.
Could this be a temporary situation with intention of restoring old content to the new software (perhaps when they have sussed how to do it)?
When it seemed LPGforum could be taken down at any time with the possibility of all that content being lost I asked my son to come up with a way of downloading every thread completely and he managed it... Not needed now as LPGforum has been saved but I still have all that data backed up and I'm sure we'd have come up with a way of including that content in a new forum if LPGforum had disappeared. We didn't/couldn't download user accounts, an implication of that being that the old content would have to be available on the new forum just as some sort of archive, but we'd have done all we could to make the archive searchable.
Edit - Hehe I started writing this post just before a customer turned up, finished writing after the customer left... Probably a bit out of touch in the light of recent posts it crossed with.