This approach and Werner's are almost diametrically opposite approaches to remastering, and suitable for very different purposes. And if "remastering" means creating a new ISO image for CD/DVD, this is of course not remastering at all.

But, in my understanding, remastering means essentially recompressing a modified UNIONFS, possibly together with other modifications. That's what I and a few other users need, and provided the necessary boot files are present, copy/backup by the built-in Install Knoppix to flash disk can be used.

As for virtual machines, I have found qemu very useful for checking the remastering, but personally, I don't really need them when I don't modify minirt.gz. Nor have I ever needed a hard disk install for remastering. That was necessary to build a pure 64 bits Knoppix version in a straightforward way, but that's a different story.