My brother owns one for his Glock 17 which he uses for Home Defense. It's actually a pretty sweet little setup which I would like to get for one of my pistols, but unfortunately the only pistol I own that has a MCK available for it is the S&W M&P40 Shield, and it just seems kind of pointless to get one for a single stack concealed carry piece like the Shield.
If they made one for the SW40VE or better yet the H&K USP, then I would be all over that, but unfortunately they don't.
As most things firearm related --- Beauty or (need) is in the eye of the beer holder.
for me its like "For What"?
if i am going to try to manipulate something that size I will just grab my shotgun or AR 300 Blackout.
I see this as similar to my ruger charger, a good platform for my wife and kids to be able to get used to firing a pistol without needing to hold up a "heavy" pistol and deal with recoil. I also see this as potentially a superior way to give my wife and kids a way for them to be able to deal with home defense.
When I was single I bought and shot 10mm generally. When I got married that didn't fly anymore, and then I found myself having a 380 bersa and now a few 9mm pistols. Kids and wife just can't handle the hotter/bigger rounds without a lot more training.
If you want to go from scratch my suggestion is to pick up a taurus g3 (if possible with rebate) and add the taurus version of this caa mck. Can be had for 200usd from here: armsunlimited.com