I have used the eppler169 airfoil, never have the oportunity to put my hands in the coordenates of the double reflex airfoil of the diablotin but the one I use gives me nice results, stable upright and inverted elevators and very slow flying but it will not instant break at idle; after the crash I added a little dihedral to correct pitch down tendence with rudder and now it does nice stationary flat spins!!
If you have the chance to modify the tail add airfoil to the stab it sure worth the effort, more authority AND more control
The wings are made of 1 piece
Thanks for the interest