I think you will be fine if you fly at about half throttle but if you try to go too fast and have too much pitch on your prop I think the first thing to go would be your ailerons followed closely by your elevator if by saying 1 servo for the elevator means 1 servo for both elevator halfs ( not one on each elevator half). As to the rudder I dont think that is powerful enough either. I am also getting a DP extra and I am putting a moki 2.1 on it. Here is my setup on the servos-one 8411 155oz servo on the inside of each aileron, one 811 56oz servo on the outside of each aileron, one 8411 155oz servo on each elevator half ( admittedly this is about 50oz on each elevator half more than you need) and one 8411 155oz servo on the rudder.