WIth the foil-side facing. JC: as you said - "This RBS reflects back infared radiation back to the plywood that would normally be transmitted to the attic." WHERE does the heat go??! It goes back INTO the plywood, no? If it does, then the plywood is going to get super-heated from this process. This is what I (we) are saying is happening to the sheathing. This 'reflection' will accellerate the aging process of the sheathing AND the shingles. I've quoted, already, where it's important that IF the heat is absorbed INTO the attic, it needs to be ventilated. I didn't make this up.
And in your example about the fire fighters, the foil reflects the heat back towards the air that 'it came from'. I'm sure if you measured the air immediately 'outside' of the foil sheet (in this example), you'll find that it's HOTTER than air that's, say, 10' away. I ask again - WHERE does the heat go in the attic that's reflected BACK towards the sheathing? And in answering this, what does it to the 'material' that's between the reflective barrier AND the outside air??!