Is the rate of paint consumption really that much higher, or is it just that you're getting to play more paintball? How many minutes paintball is 40 points, what was the average duration of the points?
The total number of minutes play, multiplied by the number of players on the field, and then that divided by the number of boxes used would give you a rate that you could compare with the 7 man.
I'd be supprised if it was anymore than the 7 man per minute of play, per player.
EDIT: Okay that's weird, when i posted this it appeared earlier in the thread than the ones i posted last night? Is the clock screwed?