I have a confession to make....
I have never used a canister filter... EVER! I've only used powerfilters/overhangfilters and in-tank filters for turtles. Oh, and I've used the barrell-style in-pond filters in a koi pond.
Frankly, I'm a little scared of the whole concept of water leaving through tenuous tubes and into a concealed box. The proabability of error (e.g. draining your tank while you're not home to catch it) I find terrifying. They also are a much higher investment and if I can never get it to work for me the way it should, that's a lot of money down the drai -- not to mention frustration. I worry too that I wouldn't know what attachments, pieces, and parts to buy, and would end up trying to rig something up that woudn't really work.
I'm such a wuss.