We did the Backstage Safari twice, we enjoyed it so much. The first year we went, in 2001, it was somewhat unorganized (I think they had college interns running it), but still very good. Last Oct, they had hired a retired highschool teacher to lead us and it ran much smoother. They also focused alot more on the contributions Disney has made to conservation efforts (almost trying to sell us on the fact they were on top of it.) But, the information you learn is great, the opportunity to see animals (elephants, giraffes, etc) up close and better yet, to have the opportunity to touch a white rhino is more than worth the price of the tour , IMO.
Oh, we also did Keys To the Kingdom. Loved that one, too!
No matter what, you will get a great tour experience!