I've had both Aimpoints and an MRO on my carbines. I used the same H-1 on a 223 pistol and currently on my MPX. There was very little shift in balance or noticeable weight before or after I mounted it. The pro however made a noticeable difference in weight and balance and I didn't care for it at all. If I were to buy a second MPX or another pistol build I would use an MRO. Definitely prefer the larger field of view and ease of adjustment.
A pic of my buddy's twin to my AR pistol and a pic of my MPX
https://uploads.tapatalk-cdn.com/201...48488375e8.jpghttps://uploads.tapatalk-cdn.com/201...62d6d38a6e.jpg