RE: Early Planing Board
If you are holding on to your 9m sail as your biggest, then the iS 122, or even iS133 if you really want to push it (at the expense of jibing), should do the job. Fine tuning you pumping skills maybe still will give you most in return.
Another path is to get yourself a Formula, or a really wide (90+) board and a 10.5 sail. That is of course the ultimate lightwind gear. However, it does change the style of windsurfing.