First, I would not get rid of the .22, because it is such a wonderful gun for practice, as you have found. If your hands get bad enough that's all you can handle, you'll still have it. I worked with one lady who has terrible arthritis, and she will not practice with her jframe revolver, even with light wadcutters.
I have the M&P 9 Pro and think it is a pussycat to shoot, but can't guess how it will feel to you. Even if it means driving a considerable distance to a place that rents guns, it is well worth it. If I can't find somebody locally who has one (try going to your local IDPA or USPSA matches and looking around), I'll drive 160 miles to OK City to rent a gun I'm considering. There is no substitute for actually trying it, and I've often changed my mind after shooting a particular gun.
To emphasize what I said about checking out the local IDPA or USPSA matches, these guys are helpful and will let you shoot their guns after the match. That's how I first got my hands on the M&P.
http://www.idpa.com/clubs.asp