If you intend to fly aerobatics no washout. IMO washout is a band aid for a poor wing design. With a built up wing that all the design work is already done. When I design a wing I will usually employ a couple tricks. One is moving the high point of the airfoil forward a little at the tip and increase the thickness a few percent. With something that is already designed you could radius the tip LE a bit more while making the root LE a bit sharper. The goal is to make the inboard wing section stall before the tips. Of course this takes away from snap rolls and spin entries. That being said, the way current IMAC and pattern is flown the airplanes don't stall during those maneuvers anyways. In most cases of tip stall the airplane is set up too nose heavy and has too much elevator throw to compensate.