DISE has so far been more convenient for users of the PC game. Xbox support came 2nd, but I didn't forget you. Development of STFS support has just been slow and difficult, so what you got was very basic.
You currently need to fiddle with Horizon, Modio or similar and the "(File) Contents" tab, and it can be confusing if you're new to it or if you're used to other editors saving you time. Some people have gone as far as calling DISE a joke because they thought it didn't work.
While Horizon/Modio will still be needed for a while longer, I aim to make the next version of DISE shave off the confusing part. You should no longer have to fiddle with the "(File) Contents" tab in Modio/Horizon.
This means that you should be able to drag'n'drop the ~60 KB STFS/CON file into DISE (like before), and DISE will load up your save immediately, bypassing the integrated Xbox Content Package Viewer. DISE should also repackage the file, rehash and resign it.
This can now be possible with the XboxInternals library written by Adam Spindler and Stevie Hetelekides.
Tons of credit goes to these guys! :)
Update #1 - March 29: There's progress already!
At time of writing, DISE displays Xbox saves on the character selection screen when the game storage location is set in Preference, loads STFS packages immediately, and even repacks them! Not including the rehashing and resigning just yet, but I'm getting to that next :)
Update #2 - March 29: Rehashing/Resigning works!
DISE now rehashes and resigns as expected. I'm not using just any random keyvault, and I have Stan464 to thank for providing it! :)
Update #3 - April 3: Preview
While I was at it, I started experimenting with USB devices as well. This will be in the next version of DISE, but won't save back to the USB device just yet. The UI isn't super pretty but it's a start. :)