I have and like the Ruger Mark III but I love the feel of my Ruger 22/45's and they shoot just as accurate and after thousands of rounds I'm still waiting for my first misfeed or jam. That says a lot to me right there. I don't like the feel of the new 22/45 models with the thin grips. I like the old models.
I've even thought they'd make great self defense pistols. 10 shots right in the head as fast as you can pull the trigger is pretty scary even from a 22lr.