Don't have any experience with the M&P, but from what I know of the M&P line, I'd prefer the 22/45 by a wide margin. In my humble opinion, the Ruger and Browning lines of 22 autos are the best there are and the M&P would be hard pressed to beat them.
Last edited by Paladin201; 01-22-2012 at 01:42 AM.
I do want to add an M&P 22 to my collection because I already own and shoot M&P autos. I've shot the 22/45 and it is great. I'd pick it up if the cash price was good but I wouldn't trade or sell the Ruger for it.