The Bullseye gunsmiths and competitors found that 9mm will shoot better groups than 45 at 50 yards at the cost of more recoil. Recoil control becomes a factor in Timed and Rapid Fire.

A sample thread from a Bullseye forum: 9mm or .45 for NMC 300

In a recent competition I got to see a military team shooter shoot a 10X in Timed Fire using a 9mm 1911 with a frame mounted red dot.