A Kryoflux is much better at preserving the image than SamDisk. SamDisk at the end of the day has to go through a floppy disk controller chip. While it does a fantastic job with that limitation it still can only read the disk as the FDC sees it.
Additionally it is limited by what information it can put into the DSK file (although it has extended it slightly to deal with some copy-protection such as faking weak-bits by storing multiple copies of the same track). Emulators often have hacks in them to spot and skip over copy protection so these images can work. You can also see the limitations if you try to write a DSK file back to a physical 3" disk and attempt to boot it on real hardware. It will often fail as the tricks it does like the multiple-copies-of-a-track can't be physically written back.
The Kryoflux is a direct USB to physical drive interface with no floppy controller. It records magnetic flux variations on the disk which let it image (or write back) any format for any machines with any copy protection in great detail (a 200KB Speccy disk images at about 8MB).
In summary: SamDisk is a great tool and it's fine for emulator users. For actual software preservation however the Kryoflux is the way to go.
Note: SamDisk also has a mode where it can produce DSK files from Kryoflux raw stream files
