FreePBX 15 is actually pretty great. I've been playing with it and the improvements are noticeable. It actually runs faster, has a far better UCP, and while I haven't tried the backup/restore, this is a big thing they were talking about being improved and I hope to get some time to try it during the next rainy days.
If Sangoma is currently hurting for QA in the FreePBX department, I recommend people get active in testing and submitting issues. Then it can more quickly get those labels of "supported" and "stable."
I don't know who's left on the paid staff for FreePBX development but I don't think it's necessarily true that Andrew and "...almost all the other Schmoozers" have completely bailed from the project. I hope that, in the spirit of open source collaboration, they continue to contribute as they have the opportunity.