Suggestion: Timed Fights?

I have a thought concerning fight design. Would it be feasible to implement fights where, rather than killing the boss, the objective is to last as long as you can?

This would act as a good check for all roles: healers would have to keep everyone topped, tanks would have to properly manage adds to keep them off the healers, and DPS would have to kill adds quickly before more spawned.

I'm not sure what the reward would be; perhaps this could be in the Proving Ground concept that was mentioned before, and you could acquire a title? Or it could be tome-related.

Just a thought.