Tip plates are the way to go. They will usually increase the roll rate because they eliminate tip losses that degrade the effectiveness of the ailerons at the most important end of the lever arm. You will also notice better aileron authority at low speeds, like on approach. I had a set of plates on a Mark's Wanderer, and a flying buddy had the same plane, but with the standard tips. He flew both and was moved to comment that mine handled much better than his and was much steadier on approach & landing. I now routinely add them to just about all my non-scale planes.