The older Nacra jibs were pretty big and would be too big for a self tacker unless you had them cut down so they could clear the mast when tacking.

The newer -self tacking- type jibs are cut much shorter on the foot and are trimmed much closer to the middle of the boat (to the end of the self tacker car track). The newer boats with self tackers have spinnakers so the spinnaker is doing the work going downwind, where as the older, non-spinnaker boats needed more jib for reaching and downwind work.

An original Nacra 6.0 (big jib) will still reach faster than any of the new spinnaker boats if the reach is too high for the spin, due to their much larger jib.