I bought the Fluval FX4 canister I was going to get the 407 since it fits better inside the stand but decided against it. What are you running?
I suggest adding a hang on Protein skimmer and even a hang on refugium. The canister is okay but The canister unit is a mechanical filter and you want to have mechanical , biological and chemical to manage proper water quality. The Fluval will polish water and trap particles via the cartridge.
Chemical is what traps and breaks down chemical compounds such as feces and uneaten food often accomplished with use of carbon and GFO as examples
Biological is what utilizes the natural process of biological filtration such as use of ceramic nuggets, bio blocks, and microscopic bacteria surfaces as examples. Best it to add or use a hang on refugium such as Reef octopus or AquaMaxx unit and even add a hang on skimmer such as ice cap K2 100