I am an LE firearms instructor at an agency with a lot of M&P guns and a constantly increasing number of shooters using RDS. I'm also an RDS instructor. I have never seen the **** on the objective lens create any real issue, even on range sessions involving hundreds of rounds in a day.
But the lens does need to be cleaned. I recommend using a "lenspen" available at photo stores, using the brush side to remove any hard particles and the cleaner side to then clean the lens. I also recommend using Zeiss, B&W or similar lens cleaning fluid with a soft cotton or microfiber cloth. Clean, all-cotton tee shirts can be cut into small swatches and used. Don't wash with fabric softener, and use an extra rinse cycle. I also carry in my bag some Zeiss pre-moistened lens cleaning towelettes. They work fine and can be obtained from major online camera stores at pretty low cost per unit.
All of these work well and I have not seen them scratch a lens, but use at your own risk. I have not conducted any formal tests and am not responsible if you scratch your optic. Do not use tissue, clothing you are wearing, paper towels, napkins, etc., and I am reluctant to use Q tips.
The Calculated Kinetics plates look interesting, but I have not tried them and they won't be approved until we are sure they cannot interfere with retention holsters. I am tempted to obtain one for T&E purposes.
No one uses the LCI hole. I wish they would get rid of it. But I doubt they will.