I'm in the experimantal stage so offer no advice yet, can't get ribs very often so lack experience.
I did a couple of racks (Beef) this week at 300-315f, no diffuser but a long way from the heat.
Very tasty but still a long way to go.
When I load pics I'll post.
I'll judge you by your actions, not what others say about you, I'll judge them by that.