Rudder/elevator-only control is quite Ok as long as there's sufficient yaw/roll coupling in the design. Quite a few US ultralights are designed that way because it can simplify wing design, I understand. One of the microlights I use for training is a derivative of the early 'Weedhopper' design, via France, by the name AX3. I tell everybody that the name is because it's predecessor design didn't have ailerons - looking inside, I reckon they originally designed the stick to control the rudder, with the pedals just dealing with the nosewheel.
Anyway, this design, as you can see in the video, uses leading edge sweep-back to give strong yaw/roll coupling and it can be flown satisfactorily without bothering with the ailerons. in fact the ailerons are very simple design and produce masses of adverse yaw, so if you use aileron for roll you need even more rudder to drive it into the turn. In that respect it's an excellent training machine because the pilot has to use rudder or the aircraft will just wander all over the sky - the aileron is just there to help balance the turn...
Tom, that is one BIG beast. I'm sure you'll enjoy flying it.
Joan