I'm pretty sure, from those photos, that the sails are sewn up in panels corresponding to the batten spacing which is also how you can get some camber in them.
This isn't how the sails for Colvin hulls are specified. They're done in vertical panels sewn with a seam every 500mm or so. That way no rip can propagate very far and the vertical seams help carry the weight of the entire sail better as they extend to the attachment points on the yard. How those sails in the above pictures are made, all the weight is on the top panel attachments to the yard alone.
They may set better, I don't know, and maybe you'll get another 5 degrees or so better pointing ability, but they're structurally weaker and the sailcloth is lighter. The cloth in my sails is about 2X the weight of that in my friend's BADGER design for example.
As I said, TANSTAAFL. In my case if I really really wanted to point higher, I'd have put a ketch rig on the hull.
PDW
I posted these four photos to demonstrate how junk sails (or junk-like wing sail) were being used on catamarans. I don't think that any of them are using cambered panels such as those that Arne Kverneland has developed.
Dragon Wings has traditional flat panels.
China Moon may have flexible battens to allow camber, but if so it is not a good system as the camber is least when wind speed is least (and you then want the most camber), and the camber is greatest when the wind speed is greatest (and you then want the least camber).
Oryx has an experimental split junk rig ('jiblets' and mainsail) with half-wishbone battens. It didn't work so well, and Pete has replaced them with something closer to the junk-wing sail like on
PHA.
PHA, (
Paix
Harmonie
Amour --> Peace Harmony Love) is a junk-soft wing sail with wishbone batten foresail and articulated straight batten aftsail. Bertrand now has a 46' Wharram, called
Grand PHA, also with soft wing sails. He is sailing it west-bound around the world from France, and now is in Australia.
This is an example of one of Arne's cambered panel junk sails, maybe on
Johanna?
Junk sails typically have very little stress on the sail cloth as the weight is carried by the bolt ropes (or bolt webbing) at the luff and leech. Because the weight is carried by the bolt ropes camber can be built into the sail panels and the panels will 'billow' into shape with relatively little wind. Also, because there is little stress on the sail cloth compared to a Bermuda-style sail, lighter-weight cloth can be used, and if a sail is torn the sail will often still be quite functional.
You can also make cambered panel junk sails with vertical seams, using a different technique from that promoted by Arne.
Note torn, holey sails and diagonal seams.
Just had to add another photo demonstrating that seams can be put wherever/however you please.
A "modern junk".

<LOL>
http://www.100days100paintings.com/...-garbage-in-our-oceans-the-junk-raft-project/