Absolutely - I have 2 fx5's on my 265 and the water is crystal clear. It is also overstocked with large Malawi predators (approx 40 fish ranging from 6"-12").
the only thing is you have to clean them often - like once a month. If I let it go 2 months - man o man - this filter sure can collect a lot of fish poo....
I also added a ehiem 2217 just filled with carbon. Not I have both fx5's using the outer foam and biomax in all three trays. I have had this setup for over 2 years and no problems - and yes it is very quiet.
Hope this helps...