Well, I am on 14385 on my SP3. It does seem rather stable. Battery life unknown as it is too early to make a call. Typing on this site sucks. There is a lag of some sort - this is on Edge. I have three extensions which may or may not be the cause. This lag does not happen elsewhere - so it could be the site.
Other than that there has been a definite improvement where heat management is concerned on the SP3 which is very welcome.
The animations are smoother and over all this build feels solid.