I'm writing a research paper on the Wiemar Republic right now. I would comment, but I have Wiemar coming out my ears right now and I'm trying to relax.
One thing is for sure, change things slightly and you'll have one hell of a ripple effect; without major effort. Hitler's rise to power was a fluke, no matter how well planned it was still a case of right place/right time. We could have ended with a up a dictatorship under Papen or total civil war...perhaps a communist govt., the list goes on.... I would love to see a clever TL about this area. Keep at it Xahar. I'll comment when my mind is less scrambled.