I don't know that you will have to clean it out that often. I used a magnum cannister filter on my old 55gallon tank and only had to clean it out once a month. Mind you, I was only using one filter pad and the rest of the filter was filled with carbon and other resins.
I found that the filter pad would have to be cleaned more often if I overfed or manaually cleaned the detritous off the live rock and substrate on occasion. Now, if you are going to use the filter as the main source of filtration for the tank (i.e. no skimmer), then you will probably have to clean it out more often. It never ceases to amaze me how much crud a protein skimmer pulls out of a tank.
I use an Xp cannister for water polishing and carbon on my 37g. I clean it maybe once every 2 months and never have any measurable nitrates,,, I think there's a lot of baseless negativity about cannister filters out there,,,, there's no reason not to use one if you have LR and/or a DSB to help with denitrification.
I use a canister filled w/LR pieces on my 200 and nothing else basically just to add surface area in the system. It's main purpose is secondary flow and chiller system closed loop. I have a 20 FOWLR w/ a canister and I maybe check it every 2-3 months. It stays pretty clean and provides more flow than the HOB filter alone. I've used canisters for years on various set-ups and believe that the benefits of being able to put different types of media in them far outweigh any negatives associated with them when used correctly.
