Yup, you're right. Heaps, Imlay, Chambers, Sandthrax, Alcatraz, etc, etc.....not extreme at all. Anyone with a rope and a weekend can do it. :roll:
Clearly there are varying degrees of difficulty depending on which canyon you choose, but in general it would fall into the category of extreme. Maybe not quite as extreme as NASCAR, or dragging clown cars on the salt flats, but in general canyoneering isn't for everyone.
YMMV