I'm a sucker for buckling springs. Dreams, though? a lighter, damped BS switch. Something with a tap, more than a click, so that I can use it in public. I'm not saying to kill the feeling, but to just make the click of it reduced (I already floss mod my M, and did my F when I had it). For weight, I'd love to see some lighter spring/hammer assemblies floating around, just so that I could see what it'd feel like.
I've heard that there are a few other things you can do to M's to silence them. Not sure though, outside of excessive foam on top and below the plate.