HI Snap

From what I've gathered over the years it used to be thought that putting the stab higher meant that the tail-plane would be more efficient if it wasn't in the wake of the wing. However at that time the designers hadn't considered the down-wash that comes from the wings. Therefore having the stab on the same line means that the tail is actually operating in clean air, to put it simply.

Having the stab higher tends to lead to some control coupling in many designs, which is why the later designs are more 'pure' to fly.

As for full span vs inset ailerons, it can be seen from the above argument that it is a matter of taste as opposed to pure aerodynamics.

Many people have shortened the ailerons in order to try and stop tip stalling in certain designs, but seeing as some maneuver's require a clean snap, then a controlable tip stall is a good thing in aerobatics. As with full size, models are designed to fulfill a specific function and their design reflects this. I have found that having some aileron in the wash of the prop has lead to better control at landing speeds, but then I have also found that barn doors for ailerons has the same effect!!

Steve