Don't own a P22, but I don't think theres a comparison between the two, with the SR22 being superior. If the $100 difference brothers you, purchase a used Ruger SR22. Rugers customer service is second to none. Here's my post about my SR22 & Ruger customer service;
My Ruger SR22 was sent in for a broken slide lock which was caused by me, not the guns fault. Being 4 yrs old & used, I had fired over 5000 rds through it and since I didn't know how much use it got from the previous owner, I requested that Ruger replace any worn parts and that I would cover the cost of any parts that were replaced. I received the SR22 back from Ruger in 10 DAYS. The description from Ruger was replaced the entire slide and all its components, the slide stop, slide stop spring and the ENTIRE frame assembly. Fired 30 rds. I basically received a brand new firearm and the charge from Ruger, $0. Completely covered under their warranty.
As far as I'm concerned Ruger owns the 22 market. My SR22 has been outstanding as well as my MARK IV's.