still have the aquastop, better priming/startup though. also supposed to have much better intake strainer (finally). i have seen a 205 on display at 2 petcos, but none for sale. i work at a pet shop and we can get in the FX5, but not the 05s yet. i googled fluval 405 and ended up at the hagen website that has a one page summary of both (the 05s and the FX5) and that lists the new changes. from what i read the FX5 doesnt do your water changes, but has valves so that it is pumping the water out, i dont know if it takes it in through that valve though.