Hi, is your sailmaker recommending this?
Just like on the main, battens (normally vertical on furling jibs) allow a sail to have more area by allowing positive roach on the leech. On headsails, the leech is normally hollow, or negative roach. This helps keep it from fluttering. And according to racing rules, ONLY JIBS can have straight leeches or positive roach. Genoas MUST have hollow.
On your boat having battens would allow more area on the leach, but you have to be careful that your rig will allow it with the same foot size. Often the leech will hit the diagonal shrouds, or the spreaders. Some boats (like the Beneteau First 35) have special spreaders (called boomerangs) to make more room. If it will not fit, you have to shorten the foot and you end up with the same area!
Check with your sailmaker and have them measure to make sure you can deal with the extra area. The other claim of better shape on a partial unfurl I've never heard before, seems dubious.