I do this. I essentially switched when they had their billing program go psycho and put several thousand dollars in hold on me.

The big thing is you need to be diligent to make sure you account remains funded so your campaigns do not get shut off.

You still have to maintain the same minimum available balance (ie your budgetx3 or your actual spending x3 whichever is lower). So it won't allow you to have a lower amount on deposit.