I think that water state is more important factor then wind strenght. So in flat water, is101 with 6.2 should be no problem at all. In very choppy water, it could be demanding at first, but when you find the groove it should be easy. A good controlable fin helps a LOT!
I find deboichet sl2 36cm easier to ride then original drake 34. You should think about fin upgrade if you are going to ride in very overpowered conditions.
I use is101 down to 5.5 with no problem.
I do not know anything about futura101