Okay, it's ready to drink!
I aged it a couple more weeks, added enough cane sugar to prime and leave about a quarter of the original sweetness. I can say fairly that the experiment was a success for the Coke at least: I got something that was both drinkable, and interestingly different from just adding vodka to Coke.
Color: somewhat lighter than the source beverage, it has a color more like that of iced tea.
Head: More persistent than I've seen in any soda that wasn't a root beer. It took some patience to get it to die down.
Flavor: Strikingly different than normal cola. It's considerably tarter and the citrus and spice elements are much more in the forefront, a lot of orange peel and cinnamon evident. Overall effect is still not unlike a spiced wine. On the down side, a somewhat chemical finish. I'm guessing it probably needs more aging among other things.
This isn't so bad - I don't think I'm going to mind finishing it up over the weekend before it goes flat again. Just the same, I don't think I'll make it again as is, though as an addition to a fruit wine or spiced beer it might be pretty good.
EDIT: Eh, I take some of it back. Maybe it's a certain sort of eccentric charm that wears off quickly or something, but after the first glass the chemical aftertaste and sourness seemed a lot sharper. Maybe it's the phosphoric acid, or who knows what else? Oh well, it was worth trying.