Well, we don't have any Mac disks to try, so let me just check: The MFS & HFS 400/800K are different only in the file system, and use the same physical recording right?
If it's only a filesystem difference, then it's already supported as the disk image we can currently export holds it. If there is information missing (like I think maybe Lisa used the sector header data?) then an appropriate sector format can be chosen with little difficulty.
If it is a different physical recording - then we just need samples dumps (using our raw stream format, which images basically anything), and a description if possible.
Perhaps it uses one of the already supported Mac physical recording formats... As you saw, we can export sector images for the physical recording from:
Apple DOS 3.2
Apple DOS 3.3+
Apple DOS 400K/800K
...plus any disk used as FM or MFM at any double or high density.
As far as we know, these should cover all the physical formats ever used by Apple for floppy disks - apart from some systems where more speed zones were used, but if we get samples it can be easily adjusted.
Well, let me be clear - we do not yet support writing. That feature is planned for a future update, but of course you should not buy based on future features, we can't guarantee how long that will take for a start.
Having said that, once writing is supported, I can't see any reason why you wouldn't be able to do that.