I can confirm with high confidence that upgrading directly from 5.2 or 6.0.2 to 6.1.1 is completely successful.
To aid future upgrades as the bootloader matures, I am coming up with a nice backup package to backup of the system 2.4gb partition. I recommend for everyone to do this before they do any upgrade/update. Then the risk is really low to upgrade to any version even when untested. If an upgrade fails it is easy to restore back to previous version you were running if you fail. More on that soon.
Jun's Alpha Loader for DSM 6.1
in DSM 6.x
Posted
It is good news, thank you very much!