To add, if your healer throws Curaga in a large party, you're going to have a much harder time keeping enmity. If the healer uses Curaga twice, enmity is not guaranteed (the fight will be over before you get enmity back or the healer will be dead).

The Cover ability from Gladiator (may be a Paladin ability if read later) on the healer and correct positioning can help in this case. For multiple enemies that use AoE attacks, this can be fatal for the tank (as you take the Cover damage first, then your own damage meant for you)

example: Weapon skills on the bugs in Toto-rak will provoke an AoE attack response. One AoE weapon skill will trigger all of their AoE attacks simultaneously. Natural instinct to use Curaga to recover from this. You use Cover on the healer. Party member does another AoE weapon skill. You now get hit by five AoE attacks meant for the healer, plus the five AoE attacks meant for you, taking double damage (and most likely succumbing at the appropriate level).

The enmity generation abilities such as Provoke, Disorient, War Drum, Warmonger, and Taunt aren't as effective as other MMORPGs. Likewise, enmity shedding abilities such as Soughspeak or Chameleon. Damage and healing seem to be king, while the enmity abilities can offset some, but cannot be relied upon the way they can in DAoC, WoW, or Rift.

i.e. rough numbers at level 50 here...

For One-on-One
A weapon skill that deals 500 damage generates 500 enmity.
Provoke II may generate 442ish enmity.
A Cure III for 600~ HP generates 450 enmity.
A Curaga that heals 400 HP to 8 people generates 2400 enmity (and for me, it seems whether the amount is healed or not, the enmity is very real).

For AoE
An AoE weapon skill that deals 500 damage generates 500 enmity on each target.
Wardrum generates 101ish enmity on each target.
Heal yourself with Second Wind or a Cure for 400 HP, generate 300 enmity on each target (Bloodbath healing doesn't seem to count).
A Curaga that heals 400 HP to 8 people generates 2400 enmity on each target.

source for enmity numbers: http://kanican.livejournal.com/54373.html

Leaving my Gladiator and Conjurer at their current levels to gradually adapt to 1.20 enmity adjustments and may have different experiences after leveling up then.