I'd like to mention that I'm experiencing a much better management of stress in the current version. Still not perfect, but definitely better.
My fort has been going for a few years - I was feeling confident in my military and bored with the lack of raids (no necromancers in this world - just by chance.) A forgotten beast composed of water entered the caverns and I took it on. It could shoot webs, but I figured my marksdwarves could take it down before that was really an issue. A few minutes later, 20 dwarves had died.
Dwarves did the thing they do and gathered all the clothes instead of the bodies - exposing themselves and their friends to extra negative thoughts. Luckily, body bits weren't causing it, as the beast preferred kicking people in the head, some teeth had been scattered about. Dwarves buried their dead and I spent some time managing labors and refilling blank positions. Three dwarves came undone - the leader of the military being one of them. They all did so either in a depressed way or far from anyone else (this fight happened about 100 levels deep, so the clean up was sort of far from the main fortress.)
Those three were a lost cause and either died or were exiled. There are 4 more very upset dwarves who I have been paying close attention to. I've given them a bit of work to do, and avoided further bad thoughts and it's working. It seems, the fort will recover, even if a few of these guys go mad later on.
This is really nice compared to 44.12. Without a doubt, this would have been a death sentence to the fort, but in my fort now, nearly a year later, the scar is there, but the wound is recovering.
Not sure how everyone else is doing, and there still remain some issue (needs and thoughts being confused, this whole thing being a bit unclear to new players), but I'm happy with the improvements so far.