In my most successful party, the Qufim party that took me 3 levels in a session (a current record), we had no real tank. A monk and a samurai in their standard orange and black kung-fu outfits were doing the job. The rest of the party consisted of myself-the white mage, a black mage, and some other classes that don't stand out. The party is only noteworthy because it had no tank. It was hell for me as a whm to keep those meleers healed. My mp was running like water.

Compare that to the Yuhtunga Jungle party I just had, where the Ninja blink tank and the paladin were so well coordinated in passing off hate, that my only real job was casting regen on the tank, and occasionally tossing a cure to wake people from the mandy's aoe sleep. I felt so spoiled. The tanks were so good, (especially the ninja) that I wasn't even necessary. And that is a first. I'm typically the player people wait on to continue fighting. There was no waiting in this pt. Sadly, I only gained two levels in this party, as it was relatively short lived once the ninja announced her departure.