In most cases, it's the keys bottoming out rather the switches. Guy in our office with a membrane keyboard who smashes the keys into oblivion is far louder than the two mechanical keyboards in the same space.
By the way, I cannot type without bottoming out, and I suspect this is something many people simply cannot learn to do. My hands will just not cooperate. I use Topre switches, which are supposedly quite ideal for practicing this magical voodoo typing technique, and when pressing a key enough to activate it but not bottom out, I have about a 50-50 chance of not activating the key at all. It's not something that's ever going to get better with practice, and frankly, I'm not personally aware of any detrimental effects of my bad bottom-out typing.
I use a topre too, and I bottomed out too, as it turned out that blues a lot better in terms of teaching you not to bottom out (because they have an audible click which provides you about the feedback of the actuation point).
you can get o-rings to dampen the bottoming-out of the keycap.
I use green switches with o-rings in a semi-open office layout and the only people who have ever noticed it are other mech enthusiasts. Browns with o-rings would be even quieter than greens.
After some coworkers complained I bought some o-rings for my brown-switch keyboard. It's much quieter although there are now other keyboards in the room that aren't quietened.
Still I like the newer quietened version, so I'm considering buying some more for my home keyboard (it is an identical model).
Learning to type without bottoming out not only will mostly elliminate the noise of brown switches but also reduce the shock tranmitted to the fingers. Ever since I stopped bottoming out (except for the spacebar and pinky-operated backspace) my typing comfort went up a lot.
Funny thing about loud keyboards. A few years ago my company had a programming pit, and I could tell when ever one of my younger programmers was chatting with a friend rather than working. His typing rate would go from 20 wpm to 100 wpm.
FYI I quickly abandoned the programming pit, back to quite workspaces for all!