I've owned an Emperor 280 and an Emperor 400. I felt both were poor quality filters. Not from a construction standpoint, but from a filtration standpoint. I think the Emperor filters are bad for the following reasons:
The water that powers the spraybar does NOT pass through the filter cartridge. This means that some of the water that the filter sucks in is not mechanically filtered at all, although it is biologically filtered.
An aquarium servicing professional told me the biowheel, in and of itself, was not a good biological filtration implementation. The biowheel has too low a surface area and is too small compared to tank volume to really make a difference.
There are very limited options for enhancing biological, chemical, and mechanical filtration. Sure, you get the blue filter cartridge, and you get the grey media container, but how much can you really fit in the grey media container? Not a whole lot. It's wise to fill it with biological media like Eheim Ehfisubstrat pro, but not an awful lot fits in there. Certainly, the media options are not as wide open as they are with an Aquaclear
The Emperor filters are loud. Especially when you first get them. Once a layer of film builds up on the impeller they quiet down a bit but they certainly are loud filters.
I'd recommend, instead of the 280, the Aquaclear 70, and instead of the 400, the Aquaclear 110.