Robert,
the reason for moving the CE of the JR a bit aft of that of the BR, is that  The CP (actual centre of pressure) tends to move forward on a junksail, with the max camber only 35% from the luff. I learned this when trying different junksails on my early boat, Malena, in the early nineties.

Arne 

PS: Anyway, there is no guarantee that I hit it, but there is room for moving the sail a bit forward or aft, if needed

Dennis, just a quick comment:

I apologise if I have made the Contessa 26 sound like a dull and mediocre sailboat. The Contessa most certainly is a fine boat which I would recommend for swift cruising. It is just that the IF, with her slimmer hull, higher ballast ratio and lower freeboard and cabin, is a hotter sailer  -  but with a cosy (read: cramped) cabin, much less suited for cruising with more than 1-2 people. I have been on board a Contessa 26, and her cabin was so much more cruiser-friendly. A couple of days ago I was also on board a Marieholm 26  -  basically an IF with raised freeboard and cabin, and spacewise this felt more like the Contessa.

So it depends what you intend to use the boat for. If cruises over more than three weeks at a time is on your mind, go for the Contessa, Marieholm 26 or the bigger Frances 26. An advantage with the folkboat types is that it is easier to replace a dead diesel with an outboard on their stern.

Arne