In reply to Augusttors:
The only problem I can think of using the Sirocco for canyoning may be that it will get scratched/damaged by small bumps and scrapes very easily compared to a hardshel helmet. That said I've never used on so I don't know for sure if that will happen!
I'm using a mammut El Cap for climbing and canyoning. I Like it as it offers a bit not protection down the back of the head than a traditional climbing helmet