When you're going to a place that specializes in reef tanks for advice, you should remember the differences between reef tanks and octopus species tanks.
If your goal is to grow sensitive corals, then you need the nitrates as low as possible. This means avoiding canister filters.
Octopusus, on the other hand, aren't particularly sensitive to nitrates, and produce a lot of them as a by-product of being messy eaters.
That's why reefcentral says no canisters, but we say they are fine. It is important that you do regular cleaning of the canister, to avoid the nitrates growing to unreasonable levels. I try to do this about once a month in my tanks.
-Mark