If you want to try a hardshell on a Canto, the Swanson seat might be the way to go because its butt area is larger than on other hardshells. Most carbon seats have a very small butt area because they're designed to be very reclined, which puts most of the rider's weight on the hips and back.
OTOH, if you're just experimenting, a fiberglass hardshell would only run around $100, vs $250+ for the Swanson.