Well just when I thought this discussion was not going to happen it suddenly comes alive! Thanks everyone for your feedback.
To Roger in particular since you have used all of the boards that I am talking about. Everyone else is welcome to provide feedback as well.
It seems that my choice now is FT138, FU122, IS122 roughly in order of price. Roger can you please describe the perfect 2 sail combo in terms of sizes for each of these boards and the relative differences i.e planing threshold, max speed, liveliness etc. Considering that I have the 12-6 SUP for non-planing conditions which of these boards will fill that 10 - 20 knot hole. Again keep in mind that when it is a solid 15 I am on my Trance but truth be told it is rarely a solid 15 in the summer here and is usually quite gusty, which is why I refer to the 10-20 knot region. In terms of sailing ability I would rate myself high advanced. Again money is afactor and I can get a FT138 plus two sails for the same price as an IS122 whcih is why I want to get a better idea as to relative performance levels i.e. twice as fast?