On a carry gun, the motion activated sights will be on all the time. Look at the battery life in the constant on condition. Most of the decent ones are 50k hours. Replace battery every 5 years to be safe.
What I should have said is in my warped own mind that if the motion detection is on with "auto shutoff" (on the dot), I would think it would save some battery life. Shows a 50,000 hour lifespan with dot at a brightness setting at "6" (10 brightness settings) BUT when running the circle with the dot, it cuts the run time down to 10,000 hours. I've found I like to keep the brightness setting around "7" or "8" depending on how bright it is outside.
Because it will by my primary carry, most likely will change the battery each year (CR1632 battery). One thing I liked about this sight after looking at it is it does not need to be removed from the slide to replace the battery.
Everything I bought was "used" from a LEO I shoot with (boxes, registration forms, instructions) as the gun was too small for him (still prefers his G19). He used the circle and dot, and I find I like that setting as well myself.
I was with him on the guns first outing and I didn't want to shoot it because I didn't want to spend the money on something, as I don't need another carry gun, but again, with my eyes, just getting to that point. Also getting to that point where I'll be selling some handguns off as I don't need them all.
Will say, have a Holosun for a AR and really like it compared to my Trijicon and Aimpoint, and the price point can't be beat along with warranty.
The 507KK-GR X2 apparently was designed for smaller carry sidearms. New, you can generally find them for around $319. So far only 250 rounds through the gun without a hiccup on my end, and my buddy only put 150 rounds through the gun no problem (generally I like to push 1k of ammo through a gun before I carry it).
Point is if your looking for a "red dot" for a handgun (this one is a green dot), for the price point, I would look at it as I've been impressed with it so far.