RE: NP Saber or Excess as biggest sail on Kombat97?
The Saber is a fast sail mainly designed for supercross : it accelerates quickly, it's very powerfull for a camberless sail and can become a bit physical to hold in overpowered conditions. It would better suit a S-Type board IMHO. If you're a heavy weight, it could be a good option for early planing.
The Excess is a freeride/freemove sail : softer than the Saber (less physical) and much more easy in maneuver/transition. This sail is a better match to the free character of the Kombat, especially if you're a light or medium weight.
As for sizing, I've tried a Jet 6.9 (ancestor of Excess 6.9) on Kombat 95 with either a 31 cm freeride fin (footstraps set outboard and back) or a 24 cm wave onshore fin (footstraps set inboard and front) and it was perfect for light wind blasting or waveriding. Now I use the same sail and setup on a Kombat 86 which is much more reactive for my light 65 kg weight.
As for footstraps placement, it's easier to learn jibing when they are set inboard and forward : easier fore/aft board's pitch and banking control during the turn which usually prevents you from stalling because you are more centered on the board. As you progress, you can move them back and outboard. To me, this changes the board character a lot, it's like I've got 2 different boards in 1.