Thanks Thomas, that does seem to be the case, but still doesnt explain why Winuae wont boot from the the Amiga hard drive when connected to the PC via USB? do you think it needs a full IDE connection instead? (somewhere I think I have a 40>44 pin IDE cable lying around)
At the end of the day I just want to backup the Amiga, quickly, reliably and easily, but if it means just keeping a copy of the files via Compact Flash, that would have to suffice. I don't have a parallel port on my PC anymore to use my old Paradise cable, so the options I have are limited.
The RDB is of not much use because it's obviously correct.
The experiment shows that the HDF is not accurate. Something went wrong either with dd or when you transferred the HDF from the Mac to the PC.
I would suggest that you create a new HDF on the PC or on the Amiga. The one you have is unusable and I doubt that it can be repaired easily.