We decided a while ago that VBulletin offered most of the features we custom built in to UBB out of the box - that would make it much easier for us to do things like forum upgrades, etc. We've been doing small alpha tests of VBB over the past month or so. In terms of this downtime specifically, VBB let us get these temporary forums set up and configured far faster than doing the same with UBB. Moreover, this will be a great opportunity for users to give us feedback on VBB and suggest features/customizations (keep in mind there are *many* "rough edges" here - our goal was to get these boards up ASAP).