In this heat of the summer - Here is an example of a huge benifit of closed spray foam insulation  . .
In our remodeled house, I have around 28in of fiberglass insulation in the ceilings. The house was build to FHA spec's durning the early 80's (1inch pink foam board as sheeting and fiberglass in 2x4 walls.
It's amazing how heat will penitrate the walls and ceiling . . .
Daughters newer home, that we used closed foam in the ceiling and walls is cool and takes hardly anything to cool and heat it (not a fair comparison, as they have geo).
The comparison is that I had to take down a smoke detector off the ceiling, as the heat in the atic was too much and setting it off. My attic has more vents on the ridge then code requires. Sofit is fullly vented to allow the air to move from eve to ridge, but, it's still too warm up there and penitrates though the fiberglass in the ceiling .. . .
Hard to make the cool air, loft up ward to keep the hot from penitrating . . . .
Yes, I have all the proper vapor barrier in place . . . .
The foam simply is a superior product and it really shows in summer heat ~