The reason I prefer the same PNR distinction is that I have friends who have actually become "friends" with someone at the airport... and got upgraded with them. (YES, it even happenned to me once!) I got over feeling like I took something away from someone else when there were 4 empty first class seats left on this US Air flight.
I believe we should be able to "carry" one person with us if we planned in advance. But feel that someone should not "jump" over others at the gate.
Just my two cents... will accept three cents in change.
William