I have not used either F122 nor K122, but from test reports it is obvious that the Futura is the pick for anyone that looks for speed, average or top. The Kode will have a much more recreational ride, and is for those that value turns and gybing over blasting.
But I have to agree with those that try to convince you to go smaller than the F122. At your weight the F122 sounds more like a replacement for the F144 than a complement. It has a sweetspot at maybe 8 m2, while the sweetspot of the F111 should be at least 7 m2.
To me, at 100 kg, a board with 20 liters plus is a very comfortable floater in all situations except halfway through the "pulling the rig". Pick the F111, you will have som much more fun (at your skill level)!