Salvete!
I'm going to be exceedingly naughty in replying to this. I used to teach a course on Koha for Rory, so obviously I'm heavily biased.
I taught twice, and as a fringe perq, he let instructors take certain courses gratis.
I would say overall that you're in for a treat. When it first started it was a small experimental thing. A lot of the students' experiences varied widely by how much they participated and which instructor they selected. Rory has gone out of his way over the years to solidify the lineup so that you get a good instructor. Compared to my University, they are WAY cheaper. They weren't as comprehensive as my University, but hey, that would be a really high bar. Also, they're designed with someone that's working full time in mind.
As far as I know, they're still using Moodle, so if you're familiar with that platform, you'll be right at home.
The time commitment will vary by course, as well. I bet that Rory would give you your instructor's email in advance to feel things out and see how heavy the workload might be.
So yeah, go for it!
Hope this helped,
Brooke
