Well, I have a Grus too, but I don't even consider that in my choice. If I'm going with such a big tank, I'm going with equally beefy coils. And beefy coils need power. Power that a single battery mod, be it 21700 or else, simply cannot provide. Even the Grus, excellent as it is, has trouble pushing even mid sized coils in dual configs. And that's with the battery full, if it's half empty it barely fires them. And I'm not gonna even mention my Drag X Plus. That thing SUUUUUUUUUCKS.
As we said when we derailed this thread before, a godsend would be a 2x21700 version of the new Gen from Vaporesso. 'Til that comes, or 'til I budge and get an Odin or something, I will keep aboard the Profile X hate train and either regret my purchase in perpetuity or find a way to make this damn thing work.