I owned one for a while. Badass piece of hardware, but, its been stated in here before, its not practical.
I traded it off for a Springfield Operator with full-length rail, that had some stuff done to it. It just fit me better at the time.
Now, I regret letting it go as I sold the Operator to my brother. So I'm eyeing the MK23 again.
TONS, of positives otherwise.
I look at it like this, if you want a gun that will survive World War 3, the MK23 is the one for you!