Personally, I would K.I.S.S. If the eventual turnover rate is the same, then don't bother with two, because it is essentially double the mess/ hassle. Double the wires, hoses, intake pipes, inflow pipes. While two filters are better for maintaining the bacteria because you clean one at a time, most people get along just fine with one filter because they don't wash all the media at once. For me, I never clean the bio media in my filter, I only rinse the sponge/ wool (just to be safe).