In Intro League II I'm running an Elemental/Sylvan deck. I intentionally left awesome cards out of my deck that cost 3 domain of either type... my MTG draft tournament experience just won't let me put em in, cause I know I'll never be able to cast them.

That said, as a general rule I don't put domain 3 cards in multicolor decks. Only needing two domain of either type, I've had no problem utilizing the current implementation of the Pantheon. If the deck synergy (a collection of balanced casting cost cards) is good, I generally won't be casting more than two cards per turn, and the likelihood of my needing two domain in both types in one turn is unlikely...and you can always flip it to what you know you're going to want the next turn, cast a spell, and then flip it to something else.