the tips are only for the look, the plane doesnīt have any problems with elevator and harriers, very satable without mixing (but you will have to mix a lot of spoilerons if you want the plane to stall nose high because of the very low wing loading, the plane just donīt want to fall of the sky). I suggest that you keep the wingtips but extend the ailerons to the tip to get faster roll rates I have aprox. 45 deg. and believe me it doesnīt roll fast but it keeps rolling at zero speed