The 3000 rpm Noctua fan is actually pretty noisy, I've got two S5's with it on them. Don't know why but it runs at 2700 rpm on one and 1800 rpm on the other at the same temps. Mine are the 140mm with adapters which move even more air.
I know they are noisy but from what I have seen it makes a noticeable difference with the stock fan, am I right?
I TESTED them I would not use them. But I don't know what it is you are looking to do with your gear. How quiet do you want? How much hash do you want?