I bought a Romeo 4 with the solar panel. I ended up returning it.

Damn mounting screw snapped. I've even used cheap $10 scope rings to hold flashlights mounted onto rifle rails over the years. I have NEVER snapped a screw before. Doesn't inspire much confidence when that happens on the ROmeo 4 when mounting it for the 1st time (I changed out the mount to the lower height mount).

Also, I had bad red glare on the rear lens ANYTIME there was light behind me. This included being outside. 1/3 of the lens was bad red. I finalloy figured out is was the part of the optic that WASN'T blocked by my head - when the light source was behind me. This issue may vary from specimen to specimen, because the sample I looked at in the store wasn't as bad as the one I had.

I returned it and got an Aimpoint. I didn't think the Romeo 4 was high enough quality to bet my life on when mounted on a homes defense carbine.

I have a 512 I bought in 2005. I've shot it from 30 degrees to 100 degrees. It's been on 2 rifles and through many thousands of rounds.  I live in South MS and we have ungodly humidity. I did have to send it back a few years ago due to the circle being dim in the center of the glass but bright on the edge.  It was out of warranty but they did a rebuild of it for $70 uncluding new glass.  I just bought another 512 last week.

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.

Honestly I'm sure it'd be fine but if they won't bother to test it to that cold of temps I won't bother buying one to test it out for them 

my eotech xps2-0 is g2g. held zero in 110 degree texas heat, and 5 degree freezing weather. I can't vouch for the negatives. I do live in TX. =)

an eotech type uses laser which consumes far more power than an LED, orders of magnitude more. I don't miss Eotech.

I wouldn't hold my breath, it's vaporware at this point.  The Vortex UH-1 should be available soon (fingers crossed).

I've been running Leupold's duty grade Deltapoint Pro motion activated mini reflex for a year or so now.   Very pleased.  Leave it on 24/7.  Screen is much larger than Aimpoint Micro, almost clear of tint.  Unobstructed peripheral vision.  I have a little astigmatism but the 7.5 MOA triangle works fine.  Rapid target acquisition, but a fine aiming point on the tip.  It is one of the final group being evaluated by SOCOM to replace the EOTech units.

I sold my EXPS then regretted it and bought a 556. I just enjoy shooting it. It is one of my "SHTF" guns, I have rechargeable CR123s and some portable solar so battery life isn't an issue. My other optics are ACOGs and Nightforce. Shit, something should still work. I might take a look at Vortex's new offering if I were you. Or the Leopold above. Maybe even a 1.5 ACOG but I didn't like mine.

I just recently found out the Steiner MRS is actually holographic, not a red dot, so you can add that to your options: a holographic RMR competitor.

Now that I know that I may well pick one up myself to try out. Got a slight astigmatism in my right eye that interferes with red dots, but holosights are perfectly fine.

Thats what I decided to do. I am waiting on the Vortex until making a final decision. Not holographic, but the new 1-8x28 accupower is also now being considered. I need hands on time with both before I arrive at a final decision.