You don't have to buy a new jib for the self tacker, they sell a clew plate you can rivet on to your existing jib that has the holes for adjustment in it. You might want to take it to a sail maker to have them get it on correctly as you will have to cut about 45 degrees across the bottom corner of the old jib clew.

I had the same trouble with the full batten jib, the top batten was too flat, so I cut it out and installed a very light strip of fiberglass and sewed it in. In heavy air I liked the mylar full batten jib, in light air the dacron jib seemed to have a better shape. Either way, it is well worth the effort to install the self tacker as it will make your tacks much faster and the crew can get out on the wire faster too. They will thank you for it!