Looking for input on the difference between the two.  I know on the M&P's the RMR sits up higher on the CORE.  Is that the same for the Glock MOS's?  I would be looking to do this on a 17 or 19 for carry.  Anyone have both and can chime in on the pro's and con's?  Thanks

I think he slide cut is more custom, than the MOS.

Seems like there's some height and gap differences when the MOS plates are used.

The RMR will sit slightly higher on the MOS due to the plate but it will still cowitness with some/most suppressor height sights. A custom cut slide sits slightly lower but it limits you to just the type of sight you have it cut for. They usually fit your sight which means even another of the same model may not fit perfect if there is any difference in castings of the housing. The MOS comes with plates to mount numerous types of RDSs so you're not limited to just the one. I was going to have one of my 19.3s cut but bought a 19MOS instead and am very happy with it. The cost of the MOS guns evens out or can be less once you factor in cutting and refinishing the slide if you choose and the initial cost of the weapon.

Random question slightly off-topic, do the MOS guns come in colored frames or black only?

Black only so far, but you can put the MOS slide on a colored frame.

I have a Grey framed G41 MOS.

Love my 19 MOS with RM02

Funny no one said the main advantage of milling. Good milling shops will fit your optic to your frame. What that REALLY does is take the reciprocating g force off of the bolts and puts I  on the optic frame. This is a far more robust operation. If you intend to carry your optic equipped gun, this is by far the more reliable and robust way.

My opinion as well. I don't have a lot of experience with red dot equipped handguns. I just got my first a little while back. I had my slide milled by Primary Machine. It took about a week to get it back. I'll definitely go this route again if I do another.

Downside is that it isn't reversible and you are married to the optic. If something comes out later, you won't be able to change.

It certainly deserves consideration before  milling. Good shops will work with you if another optic you want is larger, or if you had to switch optics due to a failure. I also had.  Cover plate made for mine fro L&M Precision so I could use the gun without the optic.