We started using ubb.classic in 2000, switched to threads in 2003 and when version 7.x came out, it was decision time. The upgrade was so major, we just had to look at alternatives to see what we want in the future.
Playing in the background with 7.x won us over, not the just the functionallity, but also this very active support forum and the stuff they do at ubbdev. The activity of the main developer on the support forum itselve gives a good trust in the future of this product.
The decision was made to stick with ubb.threads, and we backuped up that decision with an upgrade to a gold license.