The foresail on mehitabel is about 350+ sq.ft. The battens are 32mm x 3mm wall thickness. Alloy... I'm uncertain, but not a particularly stiff one. The top batten below the yard is sheeted (sometimes) and is double - that is, there's a batten each side of the sail. They serve well, for ocean and NZ sailing.
(In the main, 450+ sq.ft., 37mm x 3mm wall. Top doubled, same.)
Cheers, Kurt