I think arbitration is a way that has big risk, in arbitration we must be really careful in seeing the price difference of each market if we do not want to lose the money we have, especially the price difference between markets has started very difficult to find.
additionally, with very fast price movements make some people do not have time to arbitration according to the desired price, the long time needed for btc / alt tx confirmation greatly affect between exchangers.
the worst case is, when we buy it from "A Exchanger" and when its still at pending confirmation to "B Exchanger" the price at B Exchanger was dump