Been shooting the HS515BU and it's been GTG so far. Put a ADM T-1 mount on it and it zeroed right up with no issues. For the guy in AK, yeah I hear ya, but for the average bear in CONUS, I don't see the temp range being any problem.
Just bought another one and am coating both it and the ADM mount as speak.
I looked at a bunch of other optics, like Vortex, PA, etc. and as far as I know, nobody else has a 65 moa circle 2 moa dot on the market in a micro optic like this.
Hey if it blows up or catches on fire, I'll let you know, but so far, so good.
If you really just gotta have the halo-sight model, I'd look at the Halosun, if they shit-can the solar panel and dial in the battery life like the 515 series.