Be sure that you get some kind of guarantee that they will work to your satisfaction before your purchase them. I ordered them for my boat (C309) and found out that they absolutely wouldn't furl into the mast. I returned the sail and am quite happy with the std furling mainsail. I think that they are good in theory, especially for a Hunter which depends on a large mainsail to drive the boat, but I'm not sure that they're worth the potential problems that they could cause when furling the mainsail.
Gary