The Whisper gets clogged up at the top of the dip tube, and the bio-bags are expensive,and a pain to clean, if you don't want to replace them all the time.
The AC will leak all over the place if you allow the media to stick up above the water's surface. That's because the AC has insufficient free board above the water level in the media chamber, and also insufficient sealing around the lid. If the media is above the water level, the water can strike the lid, and it will run back and leak through the lid joint, and drip down the back of the filter all over the aquarium stand. Its a stupid design.
Maybe somebody will make a good HOB someday.