Well, part of that at least can be explained by the Red Stones that were hidden in the State Alchemist Watches, so their energy use would be subsidized in that case.
Oh. I never made that connection...That explains a lot. That never came up in anime to my recollection. Very interesting.
I guess we don't have a picture of how alchemy works after Father's influence was removed, either, since apparently he was serving as an intermediary, all energy flowing through him first before getting to the alchemists.
I can't recall if Mae ever got tired or not, using lots of the (differently-powered) alkahestry, but I don't think she did.
Oh, Right, Alkahestry... Irrc the main functional difference was that Alkahestry could be operated at range, yes? Users were typically granted a 6th sense for energy that let them track Homonculi, but was there any difference in the magic itself that would need to be reflected in the mechanics?
Not really, that I can see. Also, that 6th sense wasn't just for Homonculi; people from Shing, or at least those trained (including non-Alkahestry users) can sense Chi in all its forms (-1 Supernatural Sense), but the Homonculi have so many souls inside them they're like beacons and easy to home in on. Other than that, they can justify healing (Alkahestry's main purpose) where with Alchemy you really can't without a Stone.