Several years ago when the slide mounted mini red dot sight MRDS craze started I had a single stack 45 1911 milled out and put an RMR on it after using a dovetail mount and a Fastfire on a cheap Sig .22 1911 for a bit.
I saw some advantages but recognized there would be a learning curve involved to be as fast as I was with iron sights. Since I was still working and my outfit did not approve MRDS on duty pistols, and my eyes were still correctable, I shelved the idea.
About 5 months ago I knew my eyes were worse and I had reached the max end of the monocular Rx set ups I had been using for years. I would still shoot irons with the right glasses quickly on stages with known targets, but distinguishing people on the street and perceiving threats at distance would be very risky and land me in jail past 15 yards.
I had learned with the 45 version that in order to be effective at speed for defense shooting you must be able to run the gun flat. In other words if during recoil you cannot keep the dot in the window, you will have issue finding it and re aiming.
Well with still shooting 15oo to 2000 rds. or more rounds a month and age my elbows due to tendonitis constantly seem to hurt and I shoot very little 45 anymore. So the effort it takes to maintain the dot with the 45 is tougher these days or will shorten my sessions.
I know have about 6k or so rounds through a 9mm with a MRDS. I use a shot timer all the time and have learned to shoot a red dot as fast as I was irons.
I could go on and on as some here know I can about training and shooting but I can say this is the key in the learning process...
When using irons we have a wobble but that wobble is only about 36 inches or so in front of our eye. With the red dot you stay focused on the target and since both are seen on the same plane the dot seems to move a lot more. To steady it you must be more aggressive on the gun than most people are used to shooting especially those that only stand in lanes and shoot for groups...
You must resist the urge to ambush the shot as the dot crosses the desired impact point. Learn to minimize dot wobble accept it as you did movement in the irons and press the trigger the same as you did for the difficulty of shot when you used irons.
Dot wobble is the same as what you see if you put a laser on the gun and try to shoot. The laser dot at 25 yards dances a lot.
The MRDS is a great training tool whether you carry it not on the street. It will clean up your technique since you must get aggressive with the gun to hold steady which is the weakness in most shooters when running the gun at speed.
The times actually improve when transitioning through multiple targets since focal shift from target to sight back to distance, acquire next target, shift to sights etc. does not occur.
My experiences with different sights and those of my friends are this: for serious use there are only two so far I would trust The TYPE II RMR and the DeltaPoint.
Check this out: Long study of MRDSs
By committing to the red dot pistol I can enjoy my ARs with red dots again. I will trying the Shield RMSc soon by milling it into the slide. Will see how it holds up. The Shield is narrower and can be fit on a 1911 slide without an adapter plate.