Remember, the E.III doesn't have ailerons. Roll rate and "aileron" (aka wing warping) authority is always going to suck, and basically only serves to keep you level on takeoff or landing. You have to do the bulk of your turning and even rolling with the rudder.
Also recall that the E.III has no dihedral, so is definitely unstable, plus way underpowered. It was regarded at the time as a POS with dangerous flight qualities that was only effective due to its interrupted Spandau, and even then only when in the hands of talented pilots.
Wing warping faded into the dustbin of history so long ago that I doubt anybody has really looked at the potential problems with modern know-how. But I would suspect that once you got the wing twisted, aerodynamic loads might make it hard to straighten it out again. With very little vertical tail area or fuselage cross-section, I can see how this would lead to side-slipping into the ground. This makes me think of how the leading edge slats on Bf109s would sometimes pop out inappropriately during hard turns, resulting in undesired snaprolls.