If I may interject here about the advantages of the llamas...
consider for a moment the Aztecs who had no pack animals. They had a rather ingenius, but ultimately very fragile means of supplying their armies. They would send out runners to their tributary cities and villages and order the people along their planned route to have food and water ready for the army upon it's arrival in town. Failure to do so... well, let's just say it wasn't pretty.
If the Aztecs sent out an army 300,000 strong, 100,000 of those men would be carriers... nothing more. Sort of like a knight's squire for almost each one of the jaguar warriors. The rest carried their own supplies. As a result, they couldn't maximize their manpower for combat and they also moved rather slowly by comparison to armies that had pack animals. In reality, the Jaguar Warrior in Civ should get anything but an extra movement point.
This was also a very problematic means of supply because it meant that the Aztecs could not deviate from their planned route, and it also meant that once beyond their hegemonic borders, they had two or three days to win the war and return to friendly territory... thus, a prolonged siege of a city was nearly unheard of in Aztec warfare. The other problem was that any disruption in travel could be disastrous. On some occasions, the enemies felling cacti and trees in the narrow foot paths could wreck an entire campaign since time was of the essence.
It also became dangerous as in the case of when the Spanish showed up because it meant that many of the tributary regions suddenly rebelled and there was almost no way to supply the army at all.
The advantages of pack animals are thus readily apparent. They allow more versatility and ultimately enable longer campaigns and the freeing up of more men to fight those campaigns. And worse comes to worse, if you're stuck in the middle of nowhere, you've got extra food for another week...
