Just as an aside since you guys seem to be using his aircraft for both the tip plate as well as the swept tip concepts . . .Wayne isntalled tip plates like seanychen did on his original Raven (full scale) and he also swept the tips on all surfaces of his Turbo-Raven, and just so you know, in Wayne's parlance, these are called "Hollywood Tips" . . . why???

They are cosmetic.

The tips do alter the roll, stall, snap, and stability of an aircraft a little bit, but usually not in the direction that we would like. As in the pics YNOT posted, square, and shortened tips will increase roll rate, increase roll response and crispness, decrease roll damping, as well as roll inertia (though not by much) and in general give a 3D pilot better performance at some expense of stability in other aspects of the flight envelope. The square tips will also help for clean, crisp snap roll departures. Tip stall behaviors may change when removing tips, making the tendency a little worse and the departure more aggressive, but this won't be a constant for each wing design. The flat plates also going to dampen snap rolls a bit and reduce crispness, perhaps you will get a little better aileron response with these acting like vortex generators under some situations, and this *may* reduce the tip stall character and the rocking in harriers, but again, you will give up some snap roll performance, and perhaps some high alpha roll performce as well. The size that seanychen did are probably not going to be too much of an impact on the snaps, and they could be done so that they are easy to add and remove, so have fun experiementing (at lower speeds!) but I wouldn't expect to start seeing these on purpose built 3Ders.

Oh and the Raven also used to have strips near the root of the wing as well, sorta like the Tensor Side Force generators! (Wayne should have patented it!)

Keep in mind the Raven no longer flies with the Hollywood tips, or the tensor-esque root strips