Here's exactly what happens (and why I wanted to try the 4X2 switch in the first place):
I first started having issues once I bought my Toshiba HD-A2 player. Video when watching an HD-DVD would just cut out after 5-10 minutes. I was using the Monoprice HDX-501 5 port HDMI switch (supports HDMI 1.3 or 1.2a so it claims; regardless, it should have no problem passing 1080i video with 5.1 channel PCM sound).
The switch worked fine passing a 1080i video signal from my Rogers 3200HD cable box, as well as a Panasonic 1080i upscaling DVD player. Sound went to my receiver by Optical or Digital Coaxial.
Now, upon getting an HD player (the aforementioned HD-A2), along with the 5X1 video switcher, the video would cut out after watching an HD-DVD (or regular DVD for that matter) on the HD-A2. My makeshift solution was to remove the switch from the equation: it worked fine but of course I can't watch my HD box in digital anymore; I have to use component video which looks not so hot on my TV.
I figured this switch would be a possible answer to my prayers but boy was I wrong.
The 4X2 switch right out of the gate gave me a couple errors on the XR-57 receiver that I had never gotten before (the "U 70-1-2" error that indicates an error in being able to understand the HDMI video format) as well as occasionally giving a brief "U 70-1-1 error which is an HDCP error, but this went away as it was just because the switcher sometimes takes a couple extra seconds for HDMI handshakes to go through).
However after turning off my devices and going to play an HD-DVD again I noticed that the video would sometimes set itself to 720p on my HD-DVD player - an issue it never had. It only does this while the 4X2 switcher is connected.
My setup at this point in time looked like this:
I had the HD cable box on input 1 and tried the HD-DVD player on inputs 1 through 4 on the 4X2 switcher, output A went to my HDTV, output B went to the receiver. I also tried swapping output A and B.
No combination would work; ultimately sometimes the HD player would boot up in 720p, which my TV cannot read. The HD cable box worked fine, just like it does on my older 5X1 switch.
So, I figured, one more kick at the can, since I only need to use HDMI for audio on the HD-DVD player, why not try going out from the HD-DVD player straight to the XR-57 receiver, then out from the receiver to the switch; I could then connect my HD cable box to another input on the 4X2 switch and use either Output A or B to the TV.
It worked perfectly -- at first. HD Cable box worked fine as always.
But sure enough, sometimes I'd turn the setup on, and there would be no picture with HD-DVD and the player clearly read 720p on its display.
What a nightmare.
I really need a TV with 2-3 HDMI inputs to fix my problem - but what about if I need another HDMI port for audio (like if I got a PS3 for BluRay)? Then I'd need a new receiver because my receiver has only 1 port and I've had all these issues just trying to get 1 device to work properly using a switch and my receiver...
It really pisses me off that there's no choice but to use HDMI for video and audio (and the fact that there's so many issues with it). If HDMI was flawless, then I'd be giddy that I only had to use one cable.
But with so many compatibility issues and the whole problem with having to go through a receiver for "HD" audio which may not support the same standards (120hz, 24hz, 1080p, etc) that your TV does, there should be another path for consumers.
Frankly, my not so perfect but otherwise functional suggestion would be to bundle anything capable of playing HD video and audio with two HDMI out ports: one for the video stream and one for the audio stream. It could cause exponentially fewer HDMI handshake issues, unless of course they beefed up HDCP or added an audio component for lossless audio streams (which I wouldn't put past Hollywood...).
HDMI is a good standard, and it's a nice high bandwidth cable that effectively takes the place of DVI and is a next-gen audio cable (since it supports more bandwidth than optical or digital coax). But the HDCP handshake issues, as well as the fact that audio receivers have to also act as video switchers means that it just has too many jobs for one interconnect, and the resulting problem is all of these compatibility issues we have. This doesn't even take into account cable length issues, cable quality (many older HDMI cables, especially long runs, like in-wall cables, supposedly won't be able to pass HDMI 1.3 signals - ie. 1080p + HD audio bitstreams), etc.