Could someone explain how this would this work? I've seen talks of it a while ago, but people seem to be turned down by the speed of withdraws from exchanges. I know that you'd have to have money in both (or multiple) exchanges, but the orders are not necessarily instantly processed so wouldn't you'd have to project the price at an exchange from a few tenths of a second to a few seconds ahead of the time of the buy to compensate for the trading lag?