Some action shooting sports differentiate between "heavy" (.40 and .45) and "light" (9mm) calibres and score the lights lower. So you have to be familiar with the rules.
In IDPA, which is what I shoot, they're scored the same. So there's an advantage in 9mm being cheaper (more practice ammo) and less recoil. My Canuck 9mm 1911 is in stainless and is a good hefty piece. Now that I've received my registration, I'm taking it for a first run next week.
On the other hand... an all steel 1911 IS heavy, which affects your ability to move the gun around to different targets. I'm a bit concerned that the weight will affect my accuracy with 1 hand, especially my weak hand. Also, in 3 Gun, you move a lot with the holstered handgun. A heavy pistol needs a holster and belt that will take the weight and it will have an effect on your movement. The polymer guns are a lot lighter and you have a lot of caliber options, from .38 ACP to .45 ACP. I'm also interested in how the steel magazines for my 1911 will stand up to being dropped, compared to the ones for my M&P9, which have a rubber base to take the impact.
In the end it depends on the specific rules of your game (always play to the rules of the game) and what you shoot best. And finally, practise and more practise.