I have just bought a Belkin Flip 2 port KVM. Functionally it is almost there except I have a keyboard sticking problem. So if I type the word 'Hello' it will often (about 25% of the time) output 'Hellooooooooooooooooooooo'. If I plug the keyboard directly into the USB on the computer I don't have this problem, only when plugged into the KVM. I feel like it is a USB speed problem.
Followup It appears I have the same problem with the mouse, it will jump from one side of the screen to the other as I move it. The mouse is annoying but half as much as the keyboard.