22/45 love mine
If the 22/45 is anything like the original MKI/II's, it should always run and forever.
Not sure on the SR22 yet. Supposedly better than the P22, but?
To answer your question...buy both. you CAN afford it and you will be happy in the end.
I have a MKII and the MKIII 22/45. If I could get a MKII with a threaded barrel and rail like the MKIII 22/45 has, I would trade it off in a second.
The MKII is the stainless bull barrel, and I am partial to it because it has some heft, all stainless, no cheap plastic other than the grips, I've shot 50,000+ rounds through it since I was a kid and the only thing I have ever replaced was the ejector spring.
I do like the 22/45, but it has that stupid plastic loaded indicator cut out on the side of the chamber which is a bitch to clean, the mag floorplates are too big and clumsy in your pocket to carry around and snag on everything. The threaded is very nice though, it is a good shooter and as accurate and my MKII.
Just too much plastic on the MKIII 22/45.
I had a p22 and liked it well enough, the mag release was a little goofy, and the way the barrel worked was cheap. tiny little barrel with a shroud and it all threads together, then to put a can on it, you have to get an adapter to thread on as well. I ended up getting rid of it because 1/3 rounds roughly would keyhole after exiting my silencer and at about 100 yards they would hit like 20 FEET below my point of aim. Shot great without the can on, I think the threaded adapter and the way the barrel was just made it slightly off.
sold it to get my MKIII 22/45 and am happy I did.