So its old dead horse beating time... I believe this has been hashed out a bit before, so bear with me.
I'm in the market for a Gen5 Glock 19. I've never owned a red-dot equipped pistol yet, but I'd really like to dip my toe into the MRDS equipped pistol world. I'm trying to decide between hunting down an MOS model, or just buying a regular slide version and eventually having it milled sometime in the future.
I understand the MOS mounting system isn't as robust as a direct milled mount, and that there really isn't a standard mounting system set for such things on pistols as of now. I also understand there are some better mounting options than the OEM glock MOS plate out there, and a new one from Forward Controls that should be dropping this weekend. Being able to revert back to a basic iron sight gun, seems like a good option, if MRDS pistols are not for me. The MOS models should be somewhat "future proof" ... as Glock has wide acceptance and market share in the pistol/MRDS world, and MOS probably isn't going away soon. Glock "warranty" would stay in place vs a milled slide. If something like the Noblex/Dr Optic Glock MOS sight comes out that is lower profile, but durable (and actually works), but also direct mounts to a MOS gun without the adapter plates, I'd love to take advantage of that. I had high hopes for that sight, but it seems they had issues, and the window is very small.
The flip side is MOS guns are ( so far, locally) harder to find in stock, and command a higher price. The difference is enough of a wash that having a slide milled for a direct mount RMR or the like would not increase the cost so much that I couldn't swallow it. The bad news with milling the gun is you are stuck with whatever optic you chose, and you wont be able to switch easily unless they share a footprint. You also don't get a cover plate that you can slap back on if you decide the optic isn't for you. Glock may, or many not cover a modified gun under warranty. The mounting would be more sturdy, with fewer screws to come loose, and the height over bore and related BUIS issues are less (though the market seems to be pushing out a lot of "MOS" height sights).
I'm not really one chase the latest and greatest optic/tool/gadget (apologies, Tom), but I do appreciate the advantages of a dot sight equipped gun, having used Aimpoints on my carbines for a long time now. If the concept works for me, I likely will not be changing things unless it offers some significant upgrade over whatever I end up with. I'd like to utilize it as a carry gun once vetted. I may shoot it in Combat Optics (if I ever get back into USPSA), but gaming isn't a big consideration for me. If it works, it'll be carried and shot.
So... what are your thoughts on buying an MOS a a way to "future proof" your Glock purchase? Are the advantages of direct milling enough to sway you that way, particularly for a carry gun?