The more I use this new software, the more I think it's a shame yabb didn't keep up with development. I miss the appearance of yabb, but this is so much better in practical terms. Minor glitches aside of course.
Yeah, the clean, simple lines of YaBB made it easy/clear/usable.
We should have done this upgrade before last Christmas, but a new YaBB was looking a real possibility then (you know, you did some minor testing for me), so we delayed and delayed. Which backed us in a nasty corner, and I had to buy a new, more powerful, server as an interim bodge to keep us running

There is some hope for YaBB, which I'm not allowed to ellaborate on, but it will still be months off, even if it doesn't happen. OOF couldn't survive that in its previous form.
It was a desperately hard decision for the Admin Team to make to dump YaBB, but in reality, it was the only move we could make. It was bad for both parties - we have to learn new software, write new back-end scripts and processes, and understand the complex interdependencies of this type of system. YaBB loses one of its showcase sites - we were one of the largest (almost) standard YaBBs out there, and proving that YaBB could run quickly and reliably with really modest resources.
SMF offers us much better scalability, fits in (mostly) with our requirements, and offers far more options should we need to change again in the future.