I can relate entirely to the "better than sliced bread" reaction to a good universal like the MX-600 - my wife still considers our old MX-500 the best single upgrade we ever made to the system, with the MX-700 a step up from there.
I may be a little shaky on how the input control on your TV works, but I think I have a solution that might help. On my current TV, I have discrete input codes, so it works
very nicely, but I have a "standard" on my devices that I established at my wife's request back when we had the old TV: a button on each video source labeled "FIXTV" that would send the TV the "INPUT" command (either a discrete code for the appropriate input or a global toggle command). This way, if she switched to a source and had the wrong video input, all she had to do was press "FIXTV" until she had what she wanted on the screen. It wasn't as transparent a process as a macro using discrete inputs (which is what my MX-700 does with my Zenith C32V37), but it is still pretty user-friendly for a setup with a global INPUT command - and it's a trick that I have Mrs. gonk's full approval to share to anybody who might benefit from it.