by Rick Jerz.
Great to hear this. Right now, my Moodle site has four courses running, and around 70 students, so we are roughly the same size.
It's been awhile since I moved from 1.9 to 2.0, so I am not sure if I can tell you much. I recall moving the 1.9 course, but I had to do a lot of editing. I do recall exporting student's names, then importing them into 2.0 (without profile photos).
I think that you will enjoy 2.5.1+.
Good luck.