I love my MX-500, here is how I have my 10 devices:
1. TV (no macro, just basic TV commands)
2. SATELLITE (macro to turn TV to COMPONENT 1, Component Switchbox to Input 1, Surround Sound to TV)
3. HD-DVD (macro to turn TV to COMPONENT 1, Component Switchbox to Input 2, Surround Sound to DVD)
4. DVD-R (no macro, just basic command for recording whatever I am watching to my DVD-R)
5. PC (macro to turn TV to VGA, Surround Sound to TV)
6. XBOX (macro to turn TV to COMPONENT 1, Component Switchbox to Input 3, Surround Sound to TV)
7. XBOX 360 (macro to turn TV to COMPONENT 1, Component Switchbox to Input 4, Surround Sound to TV)
8. GAMECUBE (macro to turn TV to AV 1, Composite Switchbox to Input 1, Surround Sound to TV)
9. DREAMCAST (macro to turn TV to AV 1, Composite Switchbox to Input 2, Surround Sound to TV)
10. PLAYSTATION 2 (macro to turn TV to COMPONENT 1, Component Switchbox to Input 5, Surround Sound to TV)

My tv has two component and two av(composite) inputs so to keep everything in sync I have it switch to S-Video(which there is only one of) then to Component or Composite. That way if I'm watching a DVD which is on component 1 and I want to play Xbox which is also on component 1, it first switches to S-Video then back when I run the macro instead of the undesired switching to Component 2.