I have a Burris Fast Fire on my M&P Core and it makes for much more accurate shooting at least for me. I have the start of cataracts and wear trifocals so the red dot is great. My question is does anyone use a red dot on their edc, how long do the batteries last if you keep it on? I have to turn on the red dot on my Burris, not exactly a help if needed fast. I have the MOS slide for my G19 and would carry that if practical, but does not seem like it would be. Are there other brands more conducive to edc?