No they do not have to be cleaned more then other canisters. I just cleaned all mine , frist time in a year, and they still had lots of flow, Its all with
what you put in the middle compartments.
The xp3 cut to fit is a good thing, have that on a few of mine. The blue pad that they come with is the frist thing to throw away, Fill the centre with ceramic rings or pot scubbers, or XP3 pads, cut to fit.
Have never had a clip come unhooked.
Have never had a problem with the Drain Valves leaking.
I run them on my 120 gal , my 180 gal and on my 240 gal, never had a problem.
They are great.
Water changes thake a bit longer then 20 mins. brcause of the tank size, but draining them takes about 5 to 10 min,s.
Can not go wrong with a FX5, just wait for the right deal.