I had Fluvals 20 yrs ago they worked ok, the design is much better in these new ones , just be careful when opening them up to replace media, it is hard to pull apart and you dont want to damage the casing at the seal . By the way I love my 404.
I've got a 303, 304, and 404 in operation presently. Never had any problems with any of them. The 303 has been in operation for around 15 years and hasn't had any parts replaced yet....