We went through (yes THROUGH :E ) Morelia last Saturday about 1:00 PM. Paying too much attention to the GPS we missed the on ramp to the periferico--we were in the center lane and couldn't make the turn :S . It went surprisingly well, the Garmin RV 760 LMT with Mexico map added took us right through. All the turns were well marked. It might even have been quicker than the periferico which in past years we have always found to be busy and stressful.
Traffic was medium to heavy, no trucks. Maybe we were just lucky, though we did not see any signs prohibiting Trafico Pesado.
I'll post a new thread on the Garmin later.