I just met probably one of the best team members out there, or it might just be that I've met a lot of bad team members.
Afroken and I were going along a Tier 2 mission in which we died in a total of 12 times (I actually counted).
What stood out was that we shared hearts/consumables, split up the enemies well (we were fighting Devilites), and he never left, staying till the end.
I don't know if it's just me, but this guy was awesome.
Hearths dont (and well, CANT) have to be shared, they duplicate for each player :p