Ours is Dimension Polyant AP 360 oz, a sturdy and durable cruising fabric. We have in-mast furling too and on recommendation of several sailmakers opted for short-length vertical (flat) battens, which work well and aren't the huge pain in the ass (and impossibility to drop the sail in an emergency) that full length vertical battens are. Horizontal furling battens on the original sail did not work well at all. The sail has a straight leech supported by the battens, and no flutter. You can even have a slight roach with this, although the bit of extra sail area makes little difference on the J&J era Bavarias, as they derive most power from the big Genoa.
Ours was made by Sanders sails in Lymington and 3 years later is in top condition and we're still very pleased with it. Can highly recommend. Top quality stitching. He did have measurements on file and I've also sent them the old sail to verify and make sure it has the right fittings.
Don't forget to add leech telltales, which I've found very useful for sail trim.
It cost a bit under £2k in 2016 (for our Bavaria 40 Ocean). Peter Sanders doesn't need to advertise at boat shows, but he will give you a discount if you order around the SIBS dates.