First, I just thought I'd throw in that I like that statement in your signature about gun control. I might have to use that one sometime
But about the sights, a friend of mine ordered some a while back and I test fitted them into my MTAC. They seemed to fit alright, albeit a bit snug. However, my only concern is if you need to make elevation adjustments the company suggests you put shims (or spacers) in to raise the sight. If you end up having to do that, it MAY cause problems going into the holster. I'm not sure.
This is all just pondering from my extremely limited interaction with them, so I may be wrong.
If you're looking for sights that are great for target acquisition, you might check out XS Big Dots. I have a set of them on my G19 and KNOW they'll fit into an MTAC.