i disagree with 2 things:
1) HOBs are very effective for high waste producers like big cichlids, goldfish, and even turtles. whispers have always been more than enough for me with these things. i used a whisper 5 on a 40 gallon turtle tank with 3 4" turtles in it, then they got even bigger and i had to add a fluval 404 i had laying around (note layign around, because canisters arent that great) and it actually barely helped. if they still made the whisper 5 i would have gladly bought another, but i had to settle for the fluval 404. a canister is in my experience more appropriate for high quality water, like for more sensitive fish like discus, cardinal tetras, rays, and a lot of other things that arent that sensitive, but still not very hardy, and for very large tanks that you would need an army of HOBs for. maintenance will need to be relatively frequent on whatever filter you choose. and on my whispers, it takes me about 5-10 minutes to maintain the cartridges if i do it the longest way, and about 30 seconds if i do it the short way. at best you need to set aside about an hour to maintain a canister. and after all these benefits of HOBs, they are a lot cheaper.
2) live food making cichlids more aggressive is not just my opinion, i have seen it happen repeatedly. oscars and other big cichlids (as well as water turtles and many other animals in my experience) who are fed live food are more aggressive with other fish/animals. i had a 55 setup for a while with an oscar that got to be about 4" or so, a salvini cichlid, a couple jewel cichlids, probably a couple other cichlids (obviously they were all pretty small since they were in a 55) as well as danios, barbs, tetras, etc. because all they were ever fed was pellets, that is what they associated with food. they werent triggered to eat by the movement of fish. i highly discourage anyone from trying this combination by the way. if i had fed them live food there is no doubt those cichlids would have started to take down those danios and other fish very quickly. im not saying that if i didnt feed them for a week i could expect to find everyone alive and well, im just saying because i didnt feed them live, they werent as aggressive as they would have been if i did. that is my whole point. if you get an animal used to eating live moving animals, that is what it will associate for food and be triggered to eat by, live moving animals.