I'd like to bring this thread back on its path with this question.

Do you know of any external HDMI switch which can LEARN the IR codes to be used for switching?

This might be a wonderful feature to seamlessly integrate such a switch with whatever AV processor. Without it, one has to turn to remote control macros in order to switch both the receiver/processor and the switch at the same time. With a learning switch, the story would be totally different.

I know that Oppo switch has a "priority mechanism", but that's not exactly what I'm talking about...

I've set up an old AV switch from Radio Shack that had this capability, and I agree that it was quite convenient. Unfortunately, I don't recall seeing any switches that offer this, and some double-checking at several of the usual suspects (MonoPrice, Gefen, and Radiient) didn't turn up anything obvious.