Two standard deviations above the average is probably a better sanity check
I agree, something that is a bit more dynamic towards current market situations would be better.
Oh, and:
2% is not "insane"...
It's two orders of magnitude above most of the market right now.
No, it is not - only if you count individual offers (which could easily be a sybil/collusion attack by a single actor operating several instances with a few BTC each).
By the way, how high is traffic and volume actually? If I offer coins at relatively competitive rates, how often do these actually get taken? Daily? Once per hour? Are there historic stats to analyze?
My fee is around 0.01% and I'm involved in some 3 or 4 joins a week. FWIW.
Ok, so definitely not worth the risk then.
To earn just one single USD per day(!) you'd need to keep about 7 BTC at that rate on a hot wallet while announcing your IP to an IRC server.
Also I am wondering if it is a better strategy to put up several instances with similar configuration and effectively sybil attack the market, hoping you get more volume from people that try to "fan out" to get more counterparties involved or to pool all your funds in one large account, hoping for a "big fish" that wants to launder a lot of money at once.