In total you will have to pay 0.75% fees for all the exchanges your doing, that means once your over about 333.33$ that is already more than 2.5$. Not including the 2 withdrawal fees. Also you always have to watch all the current exchange rates on the different exchanges and beware since they may go down during the transaction time.
So I dont think its worth it.
What you wrote is exactly the number when you get a wash - everything below is worth it and above not. I don't think I can reach anyone who is just casually withdrawing +333USD from account ( I was doing just 10 SDB ) so it was aimed for anyone trying to get out let's say 10 - 50 USD in which case is Very worth it.
Nonetheless thanks for comment :)