I was in the same predicament a while back. Ended up going with a 22/45.
My reasoning?
They're proven to be very accurate and reliable.
The .22lr 1911s, not so much. Some are better than others, but where I shoot at, I can't do any live fire drills like running around and all that. I got the 22/45 to learn trigger control and test my shooting abilities out to further distances than what I can/could do with my 1911.
I agree with Dentite, my 22/45 is definitely muzzle-heavy with the bull barrel.
What it's really shown me is that if I can shoot my 22/45 out to 50ft pretty well accurate, then I should strive to get that same accuracy out of my 1911.
If you want to perform malfunction drills and whatnot, then the 1911 .22 is probably a better choice, but frankly training with a 1911 .22 is no good if you don't at least train some with your .45 as well...
I usually shoot 200-300rds of .22 through my 22-45 at the range, around 50 of .45 through my 1911, and 50-100rds through my CM9(which is my primary carry). The 22/45 has greatly improved my accuracy with my other guns, I'm shooting the 22/45 out to about 60ft and keeping it all on the paper, my other guns I'm good out to about 45-50ft so I'm still working on it there.
You'll probably find yourself shooting your .22 a WHOLE lot more once you get it, so IMO you should get a good one and make it count