We have been thinking about whether it is safe to reveal such information, but it seems that revealing an average total throughput wouldn't hurt too much. As of right now (February 2012) we have on average somewhat over 150-200BTC going through the system per day, some days more, some days less. We will not reveal the number of transactions at this time, as that would aid an analyzer in distinguishing real payouts from our internal transfers we make to obfuscate the money flow.

The warning about withdrawing amount that our internal calculations consider too big to be transferred to a single bitcoin address to be considered obscure enough is now in effect. You will see it on the withdrawal page. The actual warning limit is recalculated on a daily basis, but there isn't just a hard limit at which a warning will be shown every time. Instead, there is a window, inside which the probability of showing a warning varies from 0 to 1. This is done to make it hard for anyone, through a lot of testing, determine the limit exactly, thus exact information about the internal state of the system. Naturally, based on this setup, if the amount is very high, much higher than the calculated limit, a warning will always be shown. It is just inside the window that there is a non-100% probability of that.

The good thing is that we see that a substantial amount of users actually do follow our advice about not blindly inserting/removing too similar amounts, but instead are leaving a buffer of funds in the fog and withdrawing it at a later time so that no two input/output pairs do show a similar amount. This greatly increases obscurity for all the users, even the ones not following the advice.

Personally, it is great of course to make a little extra money on the side, but more importantly, it is great to actually have a way of anonymizing bitcoins for my other projects that I know is legit and anonymous. It is difficult to be sure of that for all the people that don't actually have direct access to our server, but at least we now provide the better functionality than the competition. Once again, I would like to thank all the users that have trusted our service and we will continue to work on staying secure and keep developing the service.