Regarding to the crowd problem in which I found last time, I've just got an idea how to solve it. Based on my previous work experience in Kantana Animation Studios, I found that I could greatly reduce 'production cost' by planning carefully about the scale of pre-production. Instead of making four extra characters, I could make just one by replacing some difference accessory, such as hat and scarf, beside changing a few texture.
I discuss this with Adam today to ensure about shared rigging. He said that it's possible. This may lead to my final decision on technique which would be used on my project.
The crowd simulation concept is very suitable. We used a software called Massive in Khankluay 2. Anyway, I think I'm not going to use a simulation software in this case because it's too expensive in production aspect. The maximum is 12 characters in a shot. Just Animation may be enough.