FWIW... the glass holes boxes are fairly noisy unless you run them with REALLY low flow. I have the 700gph box on my tank and water flowing into the box is definitely the loudest part of my system.
Functionally they are great, but I won't be buying another due to the noise. I've talked to several local reefers and seen a handful of local setups using glass holes boxes, including tanks at my LFS which uses glass holes boxes exclusively on all their tanks. They are noisy, it's the bottom line... so I know it's not just my setup.