The main use for Backup and Restore seems to be in order to "clone" a course in it's entirety including all settings. But it seems not everything is preserved.
The tickbox for "completion tracking begins on enrolment" is unset in a restored course. First seen on a heavily customised installation so I thought it was something we broke, but now also in a couple of more standard versions (v.1.1).
[I just tried it on a vanilla 2.2 and it works as expected - checkbox restored intact]
This is probably at the heart of many problems we have recently had with reporting - I find that completion tracking has not begun, trace it to this checkbox and the course creator swears it was set; then all learners have to be un-enrolled and re-enrolled (very tedious process) to begin tracking. Of course this also highlights how everything needs more testing before release.