I'll trust your judgement on that one William.    My wife also was a police dispatcher for a period in Iowa.    Admittedly a low crime town.   But she felt that most officers did not have a round in the chamber but that safeties are designed to be release with one hand and chambering a round was very swift for the officers.     

Police firing their weapons in Pella was very, very, very rare.    I remember only one such encounter in 30+ years and that was a forced entry drug bust in another city that ended up with a dead officer shot by a teenager who didn't know who was busting down the door.
I would imagine cops in Chicago might prepare differently.

I've got no experience, but it seem to me the human brain function is more important than the design of the weapon.   Really liked your comment William.