I'm not in my first production with ziva, and I can definitly say, this is definitly not an alpha version. If you know your asset and take care of the animation on your shot, their is no reason to have issue during the simulation. The only thing I can say is, their is an evaluation version, so try it. The freelancer version is not so expensive at all, so try it ! you will make your own opinion, not the opinion about all the issue you will find on a forum where we post all our issue to find a solution together... IMO, ziva is very stable, 60% of my shot are delivered with a minimal of clean-up, arround 30% have some fiew parameter to tweak, then their is arround 10% with more clean up. In production, that are pretty cool result!
About ziva RT, this is a tool to traine a machine learning from a simulation (or anything) to evaluate it in real time. But you will have to simulate some gym or posing before to you use it.