My thinking on this issue is pretty simple.
Although many argue that when the #$%* hits the fan that we revert to our training, there is also Murphy's Law. I am a strong believer in Murphy.
The reason I prefer the Glock is that when that moment comes, there is nothing extraneous to think about other than acquiring your target and making the proper decision as to "shoot/don't shoot".
No safeties, no decocking lever, no dropping the hammer on a live round, no change from double action to single action, etc. And, as a bonus, I have a high capacity weapon that has proven reliable in the field.
When stress factors are high, errors are more prone to happen, and may have more severe consequences.
For me, keeping it simple makes all the difference. LE is different than home defense, and there are myriad thoughts and activities often going on contemporaneously.
Again, this is not to state that there aren't a zillion SAO shooters out there who are much more proficient than me, etc.
When you are dealing with large departments, even agencies that qualify four times a year (like mine), the overriding consideration is safety, and everyone knows that firing a weapon four times a year hardly makes one Wyatt Earp.
My slightly more than two cents worth.
Blues