RC or CL with same wing loading/planform will both have a 5' turn. CL plans do not have half the wing loading. Why you believe this is a head scratcher unless you are equating the tensile force from the wire as a rule of thumb that it eliminates about half the loading on the plane. This is roughly true. Lift = force after all Force x time = power. Same power is required to turn and change the momentum of the aircraft in question. Difference is that the CL airplane has a wire that it can turn around due to centrifugal force allowing tighter turns as it does not have to do as much work to change its momentum and remain in the air compared to a regular plane. You will note that said CL plane slows WAY down(DRAG due to stall) when one does these radical turns whereas the regular RC plane does not as much.

As for your top paragraph, different airfoils etc don't matter nearly as much as the pilot in question. A good pilot can compensate for atrocious design. An excellent pilot can make an atrocious design look like gold. Especially in things like sailplanes. I have to laugh at the guys agonizing over the perfect airfoil. Maybe for a NATS plane, but otherwise, ha. Same with pylon racing. Its 90% pilot 10% plane.