I spotted the new North Sails Warp F2009 on a french site. The Warp has a beautiful design and there is probably nothing wrong with the performance of this sail.
The top brands in the industry are all producing high quality windsurfing sails and there are almost no sails that are a waste of your money. It all depends on your personal preferences and budget. You can check here all the pictures. Windsurfonline.fr has also posted a short movie (in French) in which they give an impression of the new North Sails Warp F2009.