I have an FX5 and a Fluval 405. They both work great. The foam inserts for the FX5 are reusable, as long as you properly maintain them and don't let them deteriorate from improper maintenance.
The only gripes I have with the FX5 is the input strainer and the location/direction of the suction cups, and the outflow nozzles fall off due to the incredible flow put out by the filter. If you don't mind altering the nozzle, then I highly recommend this filter. Lots of room for extra bio-media. I use lavarocks since they are cheap!