some of the older nimh cannot take the high burst current draw of digitals. I think it is because of their higher internal resistance, that is despite the fact that they have high capacity. With modern day nimh, you are probably fine. IMHO, since you already spring so much on your servos, why not pay a bit more for a lipo and regulator set up. Regarding the durability of such a set up, if they can survive in high vibration heli set up, they will survive on the plane.