My name is Trinomite. I own a 2011 AI and numerous other yaks that have one thing in common: They are all rigged to sail.
As I cannot be bothered to put a full sailing rig (dagger boards, rigging, etc) on all these boats I have used a V shaped downwind sail on all except the Hobie Adventure Island.
My sail of choice was a 'Scotty Mounted',http://www.spiritsails.com/
I own both sizes and these products have served me well over the years.
Please respond, if you have used these sails, or what you have found more efficient for your own uses?