I am pretty certain that, some time ago, a discussion about MSPro (during the early beta phase) also revealed that backup files could only be forwards compatible, not backwards.
Graeme
1: Samsung 12.2" SM-P900: Android 5.0.2
2: eSTAR GRAND HD Quad-Core 4G 10.2": Android 5.1
Some of my music here - https://www.soundclick.com/graemejaye
1: Samsung 12.2" SM-P900: Android 5.0.2
2: eSTAR GRAND HD Quad-Core 4G 10.2": Android 5.1
Some of my music here - https://www.soundclick.com/graemejaye