I'll stick my neck out a bit here, but keep in mind that I'm only one year into owning a C22... No, an adjustable backstay isn't important for new owners. In fact, I personally don't think it is worth even messing with until you've had a few years of sailing and can understand the implications of tuning your sails. The boat in question doesn't have tell-tales, which (I think) are much more important for getting to know what is really happening with the airflow over the sails. An adjustable backstay will allow you to bend the mast into the desired position, but if you are just starting out, you'd have no idea how to use it.