Hi.
In the full scale the horner tips and the washout helps to reduce the induced drag, so the plane can have much less drag at slower speeds. I have a Top-Flite cessna also with the horner tips but I donīt know the difference because havenīt flew any without them.
Besides this they are very beautiful and scale and I love those wing tips (offcourse you would have to be very carefull with the wing).

www.danymaia.no.sapo.pt
Best regards:
Daniel Maia