I'm building a big SM F-86 right now for a customer. I did the ailerons using an internal linkage with all the proper geometry (short servo arm and the internal horn as far from the hingeline as possible, keeping all the linkages 90* to the servo arm, etc, etc) and used metal servo arms and a 340 oz servo. I powered it up ans tested it for slop. It was pretty good....I was 90% sure it would be ok.....but for the price of the plane, that 10% of uncertainty made me do a half exposed link similar to Oliver above....now it is absolutely positive and solid with no play.....there wont be that 10% of doubt when it's flown hard. Not scale, butseeing $15K make a smokin crater because it looked great just prior to impact isn't worh it for me. There is a compromise between absolute scale and functionality.