Ive been having a 800gph eshopps overflow box and its actually pefect for me. I have a 90 gallon also and having the overflow box for over a year with no problems. Its not noisy at all . When theres not enough water going in its very easy to adjust. This is the one http://www.fosterandsmithaquatics.com/product/prod_display.cfm?pcatid=18358
Using the 300gph model myself and agree. It's perfect for me. After making a stockman standpipe, no noise issues and it matches my incoming flow. I would prefer more flow through my sump, so for a 90gal I'd agree with the 800gph model.