I just got the Linksys 4-port "Compact" KVM switch and my M$ Optical mouse (with wheel) doesn't work right - it works, but the mouse jumps around the screen and freezes at random, rendering it pretty much useless. I haven't determined if this is a wheel problem or optical problem. Perhaps the LED is pulling too much current? I connected a standard 2 button non-wheeled mouse and it works fine; haven't tried a standard wheel mouse yet.
BTW, I paid $82 for the switch at Outlook.com. It comes w/o cables, so I ordered 4 10' Belkin cables for $14 each (make sure its got 3 seperate cables, not the cheaper cables with single connector on one end). I'm having a slight ghosting problem with the video cable but nothing major for my purposes). I might just order one nice cable for my main system and keep the Belkins for the rest.