I'll just throw this out there...I've had better success with cooking the flat and point separate. Flavor, smoke ring, tenderness, etc., have turned out better when separated.
Wonder what I am missing when doing a whole packer? Not much, I suspect.
James--are you sold on cooking separate now or will you go back to whole packers? Yeah, I think so. You're onto something with your notion of an increased surface area for smoke penetration, rub exposure, etc. The only occasion where I might not separate in the future would be if I had limited grate space and couldn't spread the cuts out; a whole packer requires less grill area.