My observations have been that once they've "warmed up" the hits are definitely easier with a long gun. I've had my folks shoot our pistol course with their rifles, starting at the 25 yard line and working in so they don't know what they're doing, and almost everyone shoots 100%.
Give me four hours and I can get their short range rifle skills tuned up really nicely. They'll be working sight offset, running the safety like it's natural, and delivering quick snap shots. The problem is it might be 20 months since their last short range class when they have to use the rifle.
My problem is that a lot will struggle to get the shotgun into the fight (we require hammer back, safety on carry) and unless you remind them of it, the manual safety and sight offset on the AR are ugly (we require empty chamber, safety on carry of the M-16). The distance of the Miami fight would have likely made sight off-set an issue.
To me, it still comes back to individual skill level and the responsibility of not taking anyone's word that you're good enough - whether it's a pistol, shotgun, rifle, or super soaker.
(Our rifle course is all shot at 50 yards. 30 seconds per stage to fire five rounds - standing, kneeling, sitting, prone, high barricade, and low barricade. Target is a Transtar with a round in the 4 or 5 scored as a hit. No requirements to chamber a round from cruiser carry or to use the safety. Nothing in this prepares you for a Miami style event)