I think there are a couple of potential issues:
1. If WHDLoad patches the image when it's created, then it may well fail to work even if you can write it to floppy.
2. If the image is patched on the fly when you run the game (and the image itself is a perfect copy) then presumably you would have the same copy protection issues you would have if you tried to copy the original disk to another floppy.
Maybe if you can mount the image as a virtual floppy then you could do a diskcopy to a real disk, or use an ADF writer to write it. I have no idea whether either of those will work with the image format used by WHDLoad.
Sorry, bit vague :-/
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moto