i have a 404 running on my 110 with an AC500 and the 404 holds up well. good flow rate, easy to clean and maintain, quiet. i gave it a 4 because for the money it's better to go with a rena xp3.but if you can find a good cheap one like i did you will be happy.
Good canister filter, but I wouldn't use it as a primary filter. The features do make it a little easier to maintain than say an Eheim classic, but it's a trade off since you have to clean it so much more often.
I got a 305 and it rips ass. No more syphon ball as it has a priming pull toggle and is easy to use. Huge ass containers as well as side containers for water polish strips and such. This is a great unit that is easy to set up and maintain and so far hassle free that I think Fluval has got me as a consumer for life or until they piss me off.
I've had 304's and 404's, they are pretty good, no complaints. It's always a good idea to keep spare sealing ring around and i love the fluval skimmer for keeping water surface crystal clear.
The the good rim adapters when you order the filter to replace them crappy bent hose holders.