RE: Nuance
There is plenty of fwd/rear movement available when installing the battery tray so servo placement is not going to be a big deal. I think Andrew has his batteries over the gear plate and that is with the rudder servo in the rear and a Q80 in the nose. My demo Nuance has the batteries just fwd of the gear plate and the rudder servo in the rear and a Plettenberg Advance in the nose (lighter than Q80). Would not worry about putting the servo in the tail at all.