I have one, and thus far it's been a PITA. That said, I think the operator is 98% of the reason it's been a PITA. The biggest issue has been furling. For what ever reaon, I have more challenges trying to get that damn sail to furl comlpletely back up after using it. I'm quite sure it's me, but DAMNiiiiiiiiiiiiiiiiiiTTTTTTTTTT, it gets old.
Points of use...I've used mine anywhere from a run to in
moderate winds on a beam reach (+), however, a close reach is outside the zone, and yes it does make a difference
You're not going to be slaying any F18's, but for the SC it is a performance enhancer.
Rigging wise, it takes just a few minutes more than the time to set up your Jib.
Somewhere in this Hobie21SE/21SC forum there are pictures of my sail.
If you can't buy one from Hobie, Elliot Patterson was the sailmaker for them.
http://www.epsails.com/