OSMC with KODI Krypton?

I found out how to obtain the OSMC version from the command line (I have to use PuTTY to do this stuff):

grep VERSION_ID /etc/os-release VERSION_ID="2016.06-2"
In the meantime I also found how to set the target directory for backups in MyOSMC, so I have run it to save my config.
Additionally I have googled for a way to back up the OSMC Kodi configuration and on this page I got the advice to copy out the ~/.kodi directory, so I did this in PuTTY:

cp -R .kodi/* /media/MEDIADRIVE/backup-osmc/.kodi

Now I have a copy of the .kodi dir plus a tar file from the built-in backup on my MEDIADRIVE disk (a 1TB NTFS formatted USB disk).
If I now go ahead and execute the commands to get the testing version of Kodi:

sudo apt-get update sudo apt-get install rbp2-mediacenter-osmc
will I afterwards be able to get back to my old release OSMC if the testing version does not work properly for me?
I cannot image the complete SD-card because I don’t have a micro-SDcard reader available in my current location…

PS: I do not know from where the strange formatting of my code sections above comes, I only pasted pure text strings from PuTTY into the code sections when composing this message. DS

EDIT:
I went ahead and edited the /etc/apt/sources.list according to the instructions for getting the testing version. But before running the install I wanted to make sure I was on the latest OSMC release (mine was from June) so I made a dist-upgrade.
I screwed up apparently because now MyOSMC has disappeared and Kodi system info says I have Kodi 17 beta1
Is there a way to get back the MyOSMC program add-on?