I have mixed feelings about them but generally like them overall. They're UK Sailmakers Tape Drive sails that use a tinted (UV-reducing) mylar sandwich base with aramid scrim embedded, and carbon fiber tapes are laid on the surface of both sides in the directions of maximum stress.

On the plus side they're an excellent shape and I don't think the shape has changed since they were new. They are near-zero stretch, despite some hard sailing (e.g. double reefed 45 knots apparent -- gusting into the 50's for 6+ hours at a time in significant chop).

The aramid scrim and mylar base is holding up well, after 6 years use, but the CF tapes are showing signs of adhesive breakdown along the longitudinal edges for the entire length of each tape, only on the main. I brought it in for service two winters ago (after 5 years use) and they went over the top of the areas that were separating by adding wider clear adhesive tape. I think it needs it again this year, and I think these sails will be candidates for replacement in another two or three years. (8 or 9 years total life).

My light air genoa (screacher) is a North Sails 3DL and I like that construction better, but I don't think they got the shape right. The screacher isn't as good a performer as I'd like, and it's a candidate for replacement just to find a better performing sail.

Here's the NorthSails screacher: