I've been going through each hard dungeon one by one just to clear them from the journal log.

In every dungeon, every tank does try to speed pull, though some ask first.

My suggestion is that if you are appropriately geared or overgeared, A WHM or SCH should be able to keep up with a tank provided that:
a) The tank has all the enmity and keeps it.
b) The DPS are not Melee type. And the both the Tank and the DPS avoid AOE's

If the tank kinda sucks, then they shouldn't be trying any kind of mass pull. If the DPS are under-geared or can't get out of the way of the AOE, then they won't kill the mobs fast enough for the healer to save the Tank from being killed.

The most efficient use of MP for a WHM is to use only Cure I until a freecure pops then use Cure II, but masspulls inevitably require spamming Cure II on top of Regen which burns MP faster and causes Enmity to raise quickly.If the WHM has to do the full Devine Seal+Presence of mind+Magica II before Regen and Cure's, then the tank is pulling too much and will have trouble keeping enmity.

So parties really have two options for speed pulling:
a) Healer Race - Where the Tank has to hold enmity while the healer spams healing spells. A wipe will happen if the Tank dies or loses enmity.
b) DPS Race - Where everyone uses AOE's including the healer to prevent the mobs from moving or doing damage.

If you have Melee DPS, then you're better off not speed pulling, as the healer will not have time to heal them. From experience, as a healer, the largest pull possible is determined by how large the mobs combined AOE is. If they only have linear AOE's then you can still do a large pull. If they are center-AOE's then Melee DPS will not be able to deal with multiple AOE circles without taking damage and still dealing damage.