Using
delta encoding, would it be possible to patch the existing Hornet model to add the
collimated HUD Umberto created after release?
bsdiff and
xdelta both sound like they're capable of creating patches for binary files. FSX MDL files are stored in a RIFF container, and I don't know what would happen if you ran one of those tools on one. I'm definitely not an expert on file types, so I'm not really sure what I'm talking about. Just thinking out loud...
(Edit: Really just a question for Umberto, I guess. Doesn't seem of much use in any other context here.)