As much as I hate gearscore because of its generalization, it is handy when a pug starts to mouse over, and see what you are up against. When im tanking and I see a high GS healer, I rush in like Leroy Jenkins and make huge pulls and have a blast. When im just a solo DPS I love it when the tank does the same. Huge pulls for my tank is the only way I'm not mana starved.

My rule of thumb is that if there are at least a geared tank healer and one dps, it will be a very smooth run. I did have a couple of healers try to heal in a DPS spec while attempting to add DPS.... never works out too well.