I'll chime in with my experience with canister filters and have just posted about my issue not too long ago.
Now mind you I work on the Mississippi river and its not your typical 9-5 m/f kinda job and we have 5 month old preemie twin boys. So water changes and filter maintenance don't get completed as much as I or one would like due to my work/life schedule. I have been fighting with tank nitrates since the tank was born it's about six to seven months old now. I couldn't figure out why, well till I found this forum. See, I run two Fluval 404's on a 125 gallon prior freshwater. *we got the complete setup for FREE*. I was running all sorts of product in the various media compartments. The nitrates would drop for 7-8 days then spike to off the chart, API test kit.
So here is what I did, I got rid of the Fluval filter pads that were in the canister and now just run carbon and a seachem bag/pouch. Guess what? My nitrates are down to 0.0 and have been since I have been home this past week and half.
I agree that if you can do your maintenance and stay on top of it, you won't have a nitrate farm like I did. The filter pads work great, and would always be filthy with, well you know. Since I have removed the pads, my Reef Octopus protein skimmer has doubled its production.
I hope my lil experience helps you in your decision, I am still a novice in this hobby and enjoy it 100%.