I thought the Pro 2 was really quiet, but I'm used to louder switches so that might be why.
i think the pro2 spacebar is loud as fck, even on the type-s version. i lubed it and that helped, but it needs even more suppression in my opinion.
but i guess it's more the contrast, and not the spacebar itself. because all the silenced non-stabilized keys are really really quiet, and then the spacebar is just 30 times as loud.
it drove me crazy, to the point where i stopped using it. now that i've lubed it, i can use it again, but i'm still not satisfied with the sound of that spacebar.
the reason i think it's the contrast is because i can happily type on a IBM F without getting annoyed by anything. but that hhkb spacebar, omfg..