We have over 600 of the old 500 series EOTECH optics in my work area. Most of these have been in near constant use for years and still work fine. Problems with emitters falling out inside the optic do pop up from time to time. Other problems exist such as delamination of the glass. Other issues, like loosing the little rubber battery bumpers, pop up too.
We've slowly (as budget allows) been trying to replace all the old optics with newer stuff and have a couple hundred SIG Romeo4M and 4T models issued out as well as a bunch of Aimpoint PRO and T1/T2 optics. The PRO did occasionally have issues with the mount not staying tight but Aimpoint replaced our mounts under warranty. I think to date I've seen one Romeo fail. It would not produce the center dot. Only the outer ring would illuminate. So the optic still would have worked in a pinch.
The newer EOTECH sights made after 2016 should be good to go and the optic seems to have been generally refined. With that said, I think I'd take a good look at the Romeo4T if I wanted a new red dot with a circle dot reticle. Nice size and weight. Good battery life and common T1 mount options. Price is usually just a bit under $400 from online retailers.
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