Quoted:
Blair,
If you want to build a 3-gun kit, the RMR would not be the best option. That is, unless you want to shoot in Open and I take it from your post that you are new to 3-gunning.
At this time, you're better served to look for a 1-4x variable scope for your AR, leave handgun as-is and get a semi-auto shotgun. That would be the quickest and cheapest way to get started.
Well, I am getting older (47) and shooting irons is getting more difficult. I started using fiber optics on my skeet gun and handgun and that has helped. I tried a friend's J-point mounted on his Glock and REALLY liked it. So I am warming to a reddot sight on "other guns". I'd like to do an RMR on my Glock 20 for pin shooting.
That being said, you can run 3-gun with a reddot/reflex as a really close quarters option to a fixed power optic. Either the 45 degree strongside cant mount or an on-top. My 3-gun carbine runs a NF 1-4, but a buddy of mine has a Trijicon TA33 and a J-point on cant. His set up is lighter and cheaper than mine. Even if you coughed the bucks for an RMR it would still be lighter than a 1-4.