its not the biowheel itself that is the problem with those filters.
its the cartridge media and lack of media space contained in the filter compared to an Aquaclear or a canister that is the problem.
eg the largest Aquaclear (110) can handle quite a load. The largest penguin cannot handle nearly the same load - the cartridges will clog quickly if you have messy fish.
Aquaclear is an HOB, and the best on the market. Not only do they provide great filtration, but they allow you to customize your filtartion to your needs, and they are very easy to maintain.
i have a bio-wheel filter its nice i have the tetratec pf150 (what a joke) running on the same tank. the bio-wheels are nice but you still can't bet a sump, or drip.
As far as HOBs, I go with Emperors. I have had 3 ACs, and all three eventually got very noisy and stopped working all together. I will admit, the AC110 I had broke because of sand- sand will bring an end to any HOB.
I am happy with my Emperor 280 and Emperor 400. They both do a great job.
Ewurm - I have used penguins for most of my tanks and they work perfectly. World of Fish in MN recommends them. The penguins also have new models that can hold two cartridges now. I also use the Whisper filters and I love them. Anyone else use Whispers?