I'm ACN lv20 now, I studied a lot the two Crabuncles, and now I can say that while Emerald is a fine DPS, Topaz is a wonderful tank *^*
He takes reduced damage and takes lots of aggro.
Every time I try to make him tank, the party's tank gets upset and says "do your job", but during a Guildhest I used it anyway and no one had a single HP damage :O
I saw the tank DPSing and the CNJ just walking around, while I was DPSing as ACN and casting a Physick every once in a long while.
But still, I'd like some advice from any experienced ACN/SMN/SCH about this: should I let Topaz tank in dungeons or should I always use Emerald when I'm in parties?
P.S.: Looking forward to Titan-Egi *^*