Ah sorry - I misunderstood you.

Seeing that edit, I could be wrong, but I would update from the 3.3 partition, and in theory you should be able to switch back to your other partition (2.15) using switch.sh.

I also believe downgrading is feasible using the remarkable-update server. Just don’t open any important notebooks in 3.8 until you’re sure you want to stay on that version, there’s a new file format that isn’t backwards compatible, and your notebooks get converted on opening.

There’s a new rmHacks that’s working to mirror most of DDVK’s features and adding more that has been working great for me. They’re up to 3.8 right now.

DDVK seems to have abandoned the project.

https://github.com/mb1986/rm-hacks