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I've been shooting USPSA with red dots since the turn of the century. (Doesn't that sound impressive;-)

The C-More on my open gun has a VERY large dot. At pistol distances larger dot's are quicker. It uses a 1/3N battery.
My Ruger Mark III has a variable sized ULTRA Dot. I only switch to the smaller dots for finer work. For Steel Challenge, I used the largest dot.
My current AR has an inexpensive dot. It was under $100 but it's been a while. This AR also has side mounted Iron Sights.
I have an eotech on another AR. The batteries leaked. I cleaned it up and replaced parts. Now, I keep the batteries in a Zip Lock bag attached to the rifle. If they leak, it shouldn't ruin my gear.

In 2019, I put together a Carry Optics Glock 17 using a Trijicon. I got the biggest dot I could find. The feature I like is the automated on/off. It uses a 2032 battery. (Several of my dot scopes use the 2032.) I put a note in my calendar to change ALL the batteries in ALL of my dot scopes sometime this month. It's been a year. The feature I don't like is taking the scope off to change batteries. It means a trip to the range to sight it in afterwards.