MOST sedums are ok. Here is what TTT says about Sedum Acre/Album which is the bad one:
"Sedum Acre, which looks very similar but has yellow flowers and should not be fed to tortoises as it contains toxic piperidine alkaloids. If you are not sure that your plant is Sedum Album then it might be wise to refrain from feeding until a positive identification is made."
My torties LOVE Sedum Brevifolium, they go crazy for it. I just recently bought Sedum Tricolor, but it is detoxing now, so I won't know if they like it for a few months.
I know that there are LOTS of different types of Sedum. Upon researching it, I found a whole lot of conflicting info and basically decided NOT to feed any of it, until I meet someone who knows the difference, and has fed out a particular variety for a long time.