alanback: I did a test for someone on the Computers board to see how much bandwidth I used. It was a consistent 100k per minute just by making moves. I have 100 messages per discussion board page so if I'd added that to my activity it would perhaps have doubled.
I'm currently using a program to download match pages and create a .mat flie for GnuBg analysis. Because Fencer doesn't show the dice in the moves list I have to visit every page when one of the dice can't be determined from the move, so it can be 40K+ just to get a dice roll! This is easily the most bandwidth-rich gaming site I've seen.