One of the biggest problems AH has right now is that the numbers online fluctuate so much. During off-peak hours, even the 256 maps are too big, during prime time, the 512 maps are a requirement.
Overall, the larger maps are the best solution right now. They eliminate some of the furballing, but there is always a good furball for those who choose to do so. Unlike the small maps, akdesert gives EVERYONE an opportunity to do what they want to, not just those who want to furball. So while it does hurt the furballs a bit, it helps everything else vastly. On the other hand, the small maps, especially during peak hours, are completly worthless for anyone who doesn't want to dive into a 50 player furball.
Another big problem is tactics. Often without missions, the players are clueless as to where to go(Sheep, all of ya) The small maps there is almost always a clear direction that is best to move in, on akdesert, there are so many possible places to attack, that a coordinated attack can be difficult. The 512 maps are maps that the players have to learn to play, it's far more complicated than the 256 maps.
The best map size right now is probably something between 256 and 512. Future maps will need to be designed for 500 players, as much as for 100 players, a difficult but possible problem.