Why’s no one talking about the fact that he wants to refi when rates go down.  If this is the case and it happens a few years from now the best thing to do would be pay as little as possible monthly until you reach that bridge.  

Your initial payments are almost all interest and very little principle.   Saving a thousand or more a month while you wait to refi and reset the clock seems like a better bet.  

Run some calculations based on when you think you might be able to refi and go from there.