If were saying we cant accept .5 BTS or .1 BTS etc as the trade opening fee because the price point is too low for such an order to then sit in memory for x amount of time - why not then add a secondary pricing policy that charges over time whilst an order is left open?

Not sure if thats a better or worse solution - but it at least doesnt turn bots away at the door and penalise you as heavily for simply moving a trade.

I have something like 50,000 trades on Polo either via bot or manually - i think additional charges over the duration of an open order would have impacted me far less than the higher fees for opening/closing unfilled orders.