I don't suggest a shoulder holster for a gun that large. The Stylemaster ( I have one) is a GREAT holster, but if you want to conceal, I don't think you could do it with the MK23. You would probably print badly, unless you do some serious layering. If you just want it for tooling around in the woods, or at the range, I say go for it.
As for the drop leg, or thigh holster, they tend to migrate. Meaning, they start on the side of your thigh and gradually inch slowly towards the front of your thigh. Especially if you wear it while being very active. Running, backpacking, etc. Again, fine for the range though. The heavier the pistol, the more it migrates though. I have a 5" Springfield XD(M) 9, and the last time I took it backpacking I used a thigh rig ( Open carry is legal in NH.). Unfortunately, I regretted it. It wouldn't cinch tight enough to my leg to stay on the side, and kept heading for the front. Now I just use my stylemaster, or my American Rear Guard.
My next holster is going to be OWB. Not sure which one yet. Good gunleather will last you for the life of the gun. And Mitch makes nothing but the best. There are cheaper ones, but not better.
"An armed society is a polite society. Manners are good when one may have to back up his acts with his life."- Robert Heinlein
Some of you guys need to trade in a few of those Safe Queens and see if you can get a good deal on a Sense of Humor.- Me