Brown switches are quiet (quieter than I expected after watching youtube vids), though there is a pleasing knock sound if you're typing enthusiastically and bottoming out keys with a bit of force. It's a lighter touch than IBM/Unicomp buckling spring, the engagement point isn't as pronounced. Downside with the keyboard is that the keys go a bit shiny after not a great deal of use, however this doesn't seem to be happening on mine; maybe it's a slightly different plastic used on the blank keyset.
It's one of those, you get one and it feels somewhat different to the rubber domes you're used to. Then a few months later, for whatever reason you're forced to use a rubber dome (in my case my computer stopped working and I needed a qwerty keyboard to debug and resolve the issue), and it's at that point you realise just how dull and mushy a typical keyboard is to use and just how utterly great your Filco really is. =)
On the topic of blues/browns, given the choice I would have chosen the Cherry blue switches over the browns for the increased tactile feel. But blues are louder than browns and since this was a keyboard for work I had to take the sanity of my work colleagues into account!