I don't have any of the save games left, though I had posted a 500AD one on another thread (the romans keep kicking my a** IIRC) for someone who was interested. The main difference between my game and Clint's was the timing of the final conquest, and I razed everything while he captured cities. My Calvary invasion of the mainland was a little before his, but stalled after taking the Indian and Northern German territory. This was partly due to indecision on my part. The other factor, which in Clint's replay didn't seem to be a problem (probably due to not razing cities, and the ROP tactics I didn't use enough), was that when I declared war on any AI civ, all the others would as well, taking many cities for themselves. My Calvary defeated the armies of the Germans, Japanese, and Chinese quite easily. Most of the cities were claimed by the French, Russians, and English though. I was razing the cities I took, and then sent in a large number of settlers (~30) to claim land and resources. After a scuffle with the English on this point (if you see the replay, you'll laugh), I just decided to hold back for overwhelming tech superiority (mech infantry, modern armor) to continue. I'll know better next time
An interesting thing, I didn't build a single Knight (which I used almost exclusively to take out the Aztecs), or a single Calvary (used to take out the Indians, Germans, Japanese, and Chinese). All my Knights and later Calvary were upgraded from the original Horsemen built for the conquest of the Romans. I had built roughly 60 Horsemen, and ended up with about 30 Calvary (even after the scuffle with the English). Such is the power of 2+ movement units against the AI, that 50% of my army would remain after several hundred battles. Even during the French, English, and Russian invasions (against riflemen/infantry/tanks), the Calvary I had left almost all survived (they didn't win many battles though, just retreated from infantry and picked off a few wounded tanks for the most part). The only thing they couldn't survive was the cost cutting measures employed shortly thereafter!
On the subject of how I used my Calvary on the final war... When I captured (well, razed) AI cities, they would usually have an artillery or two. I would set these artillery out in the open, (moved them to non-railroaded sites) luring the AI to attack them instead of my Mech Infantry/Modern Armor. This left a lot of AI Calvary and Tanks out in the open for my next turn. For the most part I used my Mech Infantry to take out the Tanks and Calvary, but in some cases used my Calvary, the Modern Armor were only for attacking cities. The main purpose the Calvary had though, was retaking Artillery each turn. I don't know if this tactic made much difference, as my stacks of units at that point were quite invincible (as many as 30 Modern Armor and 5-10 Mech Infantry per stack). There are times when the AI's thirst for workers/bombardment units can be used against it to great effect though.