And I would expect an exchange or dice site to have a larger turnaround that 8 btc a month. If the turnaround of the bot increases, the fee % will be decreased.

MVDC and I asked in the chat about what % the fee should be, on multiple occasions. The answers varied from 1% to 20%. Privately we settled on 4.5% each. This was long before the jar even had 2btc depisited. We never thought that the jar would get as many donations as it did.