The main thing keeping me from testing and then using in my class Moodle 2.0 is the lack of ability for 2.0 to read 1.9 backup files as well as the ability for 2.0 to save its backup in 1.9 format. The docs say that 1.9 to 2.0 will be a feature in a future version.
It would seem like one solution would be to have a script that could read in a 1.9 backup file and output it in 2.0 format and vice-versa. Not every feature would need to be supported, just those that come from a plain-vanilla 1.9 course with no custom extensions.
I can't see any documentation on the backup file format but I want to put out the question (before I try to reverse engineer and make a hack that does this): is there a reason that such a script would not be feasible?