Here's my 2 cents.
I don't think there is anything magical about a pressurized can with water running thru it. In fact I believe anything that is not user friendly to disassemble and/or clean, is not worth the trouble. So to me, a HOB is just as effective, as long as pumpage is similar, and is much easier to clean. So unless they have somehow made canisters much more user friendly to clean well, it isn't done, and that has a much more significant effect on water quality than not.
And a stated above, I have drilled tanks with fish in them, during a water change, and it's no big deal.