[Kyo]

i learned on my 45, and the only advantage I can offer is that because its my carry gun, I was doing 2/3 things at once. My P345 was the first gun that I bought/own and I will say that instruction is more important than caliber, as long as it(caliber) doesn't take away from your learning ability.
I read about 3-4 books on shooting, self defense, and gun stuff and watched about 10-15 full length videos to try to soak it all up. Then read some forum stuff. Of course, then I practiced. It all helped out. These things that I learned on my own helped me try to reduce those things. I disagree that you need a .22 to not learn bad habits. You can learn just as many or more because of the no recoil factor. Like limp wristing, or not holding the gun correctly because it doesn't take much to handle.