A:
About noisy or quiet: I have MK710 at home, bought some years ago, and that one is quiet in my ears. I was so pleased with the keyboard that recently I bought MK710 at work, too. But that one has very noisy keys, so I am a bit disappointed. Both keyboards are named MK710 and looks the same, the only difference is that the quiet one at home has the OLD Logitech-logo on it, and the noisy one at work has the NEW Logitech-logo. So something has happened with the new ones...