Well, here's another data point for the stewpot:

I have an OFA 'Big Easy HT', which is a non-learning, five device version of the Cinema 6 and 7. When I installed the device code for my Zenith TV/VCR combo, most functions worked ok, but the 'DISPLAY' and 'PREV CH' buttons set up with their functions swapped.

I didn't have the EFCs (at the time), so I 'moved' the Display key to a temporary location (the Surround key), then moved the Prev Ch key to the Display key. Then I tried to move the Surround key function to the Prev Ch key to have everything working per their labels.

It didn't work, the remote wouldn't let me move a moved key. I tried the same thing with EFCs (once I found them), and had the same problem. It looks as a general rule that a 'modified' key can't be moved.

But I haven't done some of the things David B suggests, such as testing with a key with no function assigned (no LED flash), so there's more to check. And the Big Easy HT doesn't have learning keys, and my Cinema 7 is pretty well programmed to the max so I can't experiment with it too much anymore....

Obviously we all need One-For-All to send us free Cinema 7's so we can fully explore and characterize their every possibility, no? :-)