Topaz or Ifrit-Egi, which is useful in dungeon areas?

[Gilraen]

I think the point here is that the tank has enough work cut out for them, they don't need another tank to make things any harder. So your pet dies (alot), just resummon it. No big deal. At least resummoning doesn't come out of the healer's MP like a dead party member would.

[Lemuria]

I suppose the things you're mentioning is something that you can only learn by experience. Typically I know exactly where I can use my Titan-egi without it influencing anything, and I use it to benefit the less experienced tanks.

The best help you can do for inexperienced tanks is to give them advice. They won't learn by having Titan tanking on their behalf, it's merely a crutch.

Topaz/Titan tends to do more harm than good when summoned in a party as it can turn the enemy around to face the summoner and mages. When this includes cleave based attacks, such as gigas' swings it can easily do a lot of damage to less armored players who may not realise to move out of the way due to the constant back-and-forth aggro. It's simply bad form to use it as standard, and even your starter pet Emerald Carbuncle is preferable to a Titan summoning.

I speak here equally as a Summoner, a Healer and a Tank. I've seen the best and the worst it can do and can honestly say it has no place in a party.