I recently tried out a cheaper KVM solution, a dual monitor one with a USB hub and audio/mic support.
It seemed the perfect KVM. However, these are my experiences.
When using my keyboard via the PS/2 connection, none of my multimedia keys work (useful, because it has a volume control and my speakers do not, only on a wireless remote control.)
I plugged the keyboard in via the USB port - and it seemed to work. However, I believe to switch the hub from PC to Mac, you need to use a keyboard combo, which is only supported when the keyboard is plugged in via PS/2
Sometimes the middle mouse button doesn't work when connected via PS/2.
The multi monitor is VGA - I just found out by the looks of things my Mac Mini outputs DVI Digital only (though this is my fault!).
Mac works with 2 screens, but switching and switching back can cause it not to display on the 2nd screen unless I go detect displays again.
My question is - is there a KVM out there that supports these features?
USB keyboard and mouse inputs will full multimedia keys support
Dual monitor DVI connections
Hotkey to change PCs and physical button
USB hub
Emulate screens attached when switching to a different computer
Works with PC and Mac
Audio / Microphone support
Does one exist, that won't cost the world? So far the only one that seems to support all this (that I can tell) is this one.
UPDATE
I ended up buying the Aten CS1642. It's expensive, but it seems to work great!