I don't have much of a reference. Guardian (at my level) has difficulty maintaining AE threat. I only have 1 AE taunt and 1 AE attack. On large pulls, the Warlock almost always pulls agro with his AEs.

The guardian never goes below max health, considering he doesn't take much damage and the Templar's Reactive Heal covers what he takes.

Still too early in the game for me to make a judgement, I guess.