hi radiantx,
if you have the opportunity to try a switchblade 7,8 (or similar) on your Futura 111 before you buy do it. try with your mast, check are the cambers able to rotate, how open the leech and how can you get into plan in 13 knots? (10cm wider board gives much earlier planning than extra 0,8sqm sail) if you have good feeling take it!
cheers,
gyurmo