If the opportunity arises that a .45 and my budget permit, I'd try a .45.
I'd rather have 10 rounds of 9mm than, say, 7 rounds of .45. When all is said and done, and ballistics are minutely disected ad infinitum, I just feel that shot placement is >90% of the equation.
"The problem is not the problem. The problem is your attitude about the problem. Do you understand?" Captain Jack Sparrow.