ive seen a ton. all my barb friend started their barb as tanks. I to started out purely tanking, until recently converting/acquiring more of my gear for dps.

when most, if not all my friends has beaten the game, we hardly do massive 4player coop runs. its theoretically more efficient to farm solo with no 115% hp bonus/player.

when i was a tank, i had way less than 20k dps (about 5-7k buffed going full tanking gear coop with friends, they do the dmg, i just make sure they dont die). when i finished diablo inferno as a tank, i had maybe 20-21k BUFFED DPS.

yes, dps comes with a cost, but what makes barb so special compared to monk? (or DH, for this thread's sake)
you either pick tanking, or DPS. if you want both, prepare to fork out money. (gold or usd alike, depending on your preference of AH)

yea i had 5-7k. didnt even have WoTB to put myself 10-14 even if it only last for mere seconds and have a few min cooldown to it. i didnt even had that "choice" unless i roll barb