Yes, I have seen the Alnitak not turning off as well. That issue has been around for a long time - at least since 2.4.X. Not a super big deal for me as I do flats during the day since my setup is inside a rolloff that is dark during the day. Would be nice to have it fixed, however.
2.5.2.1 has been just super for me (other than the minor no-dither on first frame mentioned on the other thread). I installed it on a new W10 pro Skylake speed demon that I just built and it runs all night smooth as glass so far.
My only complaint is that GNS seems to be a bit overly sensitive and often comes up with alerts that are of no consequence. I get up from a GNS alert expecting a disaster only to find things running normally. But if it runs as smoothly as it has, GNS is not nearly as critical. Besides. I also set up this so I don't have far to go 
