The Petzel version is called a "Zyper". There are other kinds of energy absorbing devices, not so easy to come across in the uk, but quite common in the dolomites (not surprisisngly!). The purpose of them is to limit the impact during a fall to 6KN (I think) and thus prevent you from breaking your back/neck, or at least thats what we were told.
We also went last year (didn't take a dog, just a mate) and most of the VF's we did were in the Sella. It was absolutely fabulous and we're going again this year, but for two weeks so we can do a bit more and go further afield.