i have a 100 gallon that has 2 fluval 404's on it drilled through the bottom returned through the top.... the tank wasnt made to fit a sump under the stand so this is how my tank has to be.... but it has worked fine for me and its been up and running for 2 years... i know a lot of people like the added benefits of a sump to hide equipment such as your skimmer, heater, etc and i agree id like a sump to hide all of my stuff too.... but as far as my water quality it seems fine.... i run premium activated carbon in both fluvals all the time and my water always reads perfect.... i also have 150lbs LR and lots of corals from softies to LPS to SPS and all seem great....
its a matter of preeference i guess but my next tank will definately have a sump and one canister filter i think that would be a good set up...!!!
good luck