I'm normally pretty critical of competitive elements butting into co-op, but I think this sort of thing puts the "friendly" in "friendly competition".
It can also be informative; if you're playing a perk that is mainly suited to killing trash zeds, and someone else massively out-scores you in the total kills department, you'll think, "Hey it looks like that guy has this role covered. Maybe I should change perks and play a role we don't have?" Also I would imagine it will make people mindful of cooperative habits, like if there's a stat for money shared, you might get self-conscious about being stingy, or if there's a stat for number of ammo boxes / weapons picked up, you might realize that you haven't been sharing enough with others.... or identify other people who aren't being team-players, and quietly decide not to play with those people in the future.
However, I do hope we'll see some kind of game feature to reward keeping your teammates alive, in the future... otherwise we might see a trend of over-competitive gamer-dudes hiding behind their teammates and letting them die on purpose, just so they can kite waves solo and then brag about how many more kills they're getting. That was a common enough occurrence in Mass Effect 3 Multiplayer.
