As little as I know yet, I'm convinced that the essence + mana approach is a brilliant innovation and likely will be one of the main things praised when Elemental gets its awards speeches/posts.
However, we know next to nothing so far other than that channelers will be able to do those two fundamentally different forms of magic, the newer of which is worthy of the scary priest-kings of pre-Colombian Mesoamerica. Regardless of the special effects for imbueing essence, I'm very, very interested in seeing how the game will play differently in response to how often and how much you choose to imbue essence in lands or champions.
But I'm also seriously interested in the idea of Ludicrous-sized maps that take a ludicrously long time to play. And some talk in a few different recent threads has made me sort of hope that a channeler's starting essence is *not* all the essence he or she will ever have.
Maybe many, or even most, games will not have large enough maps and long enough calendars for finite essence to be a factor. Or maybe the starting amount will be large enough that my concern is completely misguided. But maybe, at the very least for Ludicrous maps, we should have some mechanics that can increase a channeler's essence.
It could be just a per-channeler, very slow analog to the way shards provide a mana flow, or only via quests, or some mixture. I like the idea of a mixture with 'passive' essence gains being very few and far between and quest-based gains being both darned hard to get and context-sensitive re the channeler's current overall strength.