I am a bit of a "Nahua geek" myself, but the bulk of my studies of America are more centered toward the Maya. That aside, I really want to agree with a change in the jaguar warrior as far as game play goes. They are really nothing special, especially post patches. The game is not designed in any way in which a warrior class unit is effective in any way other than to support archers. Warrior class is just to weak against much stronger starting cities. This is really evident at longer speeds, which I love to play. When I roll Aztecs, I will usually build a jaguar instead of a scout, but that is the extent of the use of this unit. I seriously doubt anyone builds many warriors, even jaguars on standard speed game-play. Most games I never build more than one, if that. Archers are the rulers of this era.
Calmecac instead of Floating Gardens? My argument is going to be a bit weak because it is still map and tile specific but instead of, or better, in addition to lakes, I would like to see a start bias toward marshes and have a bonus to them, at the very least, when worked, they are able to substitute for a lake, fulfilling the requirement for floating gardens. and in the later eras fulfilling the requirement for being camped by a river.
Sacrificial Captives? Not sure what I would change with this. My first thought would be some sort of advantage, probably cultural with puppeted cities. This was their true strength.
Last Note, Where is my Mayan CIV!