Hey Sam,
I know it's not a folding stool, but I've owned a Roc N Soc stool for years that I love. I can't seem to find exactly what model it is, but it raises high enough for me to play my upright at a comfortable level (i'm about 6'2 and i like to keep my bass pretty high). I think most of their products are drum thrones, but this one has a backrest and raises about 3 feet or maybe more. I bought it for practice, but having some back issues in the past I used it for some gigs, too. I really, really love it.