I went to the range with the XDm and the IMI mount this morning. I shot it at the 25 yard berm and it was low but seemed OK left to right. Then I shot at the target I set up at 10 yards, sloppily at first, and low. Then I adjusted the red dot the wrong dadgum way and went off the paper low. Shot it at the berm to double check. *Sigh* Yep, I adjusted it the wrong way.
I re-adjusted the Ultra Dot sight, got back on paper, settled down and concentrated on gun/trigger control, and then worked it up, one shot, adjust, one shot, adjust, until it was a hair high, then adjusted it back down a hair, shot twice, and they were touching and almost dead center on the target. Then I shot at a plastic bottle cap on the berm and I don't know if I actually hit it, but was close enough to send it flying. Nice. I like this mount. As in, Bingo! We have a winner!
While the IMI mount is plastic/composite/polymer/whatever, it is well made, stiff, looks good, fits the rail great, and has two cross bolts instead of one like the Mako that would not stay put on my particular XDm.
Oh, and the slide will come off without taking the mount off.