Ok, so the card does work (as the OZ kernel flashed).
the only reason to try another ROM would be to rule out a dodgy card (which we've ruled out now).
This is all very odd, I've managed to flash my 5500 with the 3.5.2 Opie image (and GPE image) plus the 64-0 kernel, so I can't work out why you can only flash a kernel, other than what I said above, about file extensions and md5sums.
Sorry, I'm out of ideas.
Si