I just replaced the old cheepo walmart aqua filter with a emperor 280 on my 20 gallon tank. All I have to say is wow, seems like a great filter, my 20 gallon should be squeeky clean now.
I am getting a Magnum 350 Pro setup which is essentially an Emperor 400 with canister filter combo. I am stoked. Bio-wheels are so great.
I also like that with a bio wheel you can essentially turn the wheel into live rock for a saltwater tank by placing crushed coral into the spare media compartment.