As I understand it, there are the meter movements described above.
I played with a guy some time ago who used a female avatar. The reason he gave was that he had a hard time figuring out when it was his turn because all the male avatars looked the same, and the majority of WGT members are male. He used a female avatar just to be different so he would more easily know when it was his turn.
I'm not saying it's a valid excuse; I'm just passing along his explanation.