I've had an AR equipped with a Vortex Sparc Solar in a Reptilia mount for a few months. I had several instances of pulling it out of the safe with the dot not on. I could get it back on with the up button, but it was an obvious failure of shake-awake. I also had some crazy battery drain on Duracell batteries and was getting maybe 2 months, a crazy stat for an optic trying to boast 100,000 hours. I saw enough and sent it back to Vortex. Vortex being Vortex, they sent me a new one promptly. I got the new optic Zeroed and all seemed to be well. This weekend the same thing started happening. I removed it from the rifle case after a range trip and had no dot. I turned the dot back on and put it in the safe, and when I checked it today the dot was off again.
I have no more confidence left in the optic and will likely get another warranty replacement and sell what I get in return. I like Vortex, but I think their red dots are dead to me. I've had good luck with Holosun and Sig red dots in comparison, but this may have pushed me into the Aimpoint or nothing crowd.