That really depends on several issues currently not being discussed here, such as pond design, water movement control, stocking levels and feed rates. Oh, and did I mention, every pond is different even two side by side.
tom, considering your size pond, your stocking density is not very high so that enters greatly into the equation. Many folks in this hobby can't maintain a low stocking density. The temptation to add just one more fish of a different variety is just too tempting.
While the RDF is pretty much the best mechanical filter available today, and the footprint for it, considering no other additional units are required for fine mechanical use, is so much more compact, if you already have that many sieves of that quality, AND you have sufficient space for adding additional pieces like s/g or bead filters, I think either would work quite adequately. Sorry for the run-on sentence here!lol