RE: NP Saber or Excess as biggest sail on Kombat97?
I don't know much about the NP freeride sails, so I can not comment on that.
As for footstraps, generally, the more out and back you move both front and rear straps, the more freeride/blasting oriented the board gets. You can load the fin up more and for most types of sailing, straps back and out also means you will get a better balance on the board with a bigger and more drive oriented fin. All this gives you to opportunity to lay the sail back and "lock in" for a fast ride.
Straps forwards and inboard means you will tend to stay more centered on. This is better for all kinds of maneuvers, but carving, waveriding and freestyle stuff. It is a very different type of sailing stance where you don't load up the fin as much but on the other hand are in a more ready position for the tricks.
For mastering jibes strap placement is not critical, but maybe it would still be an interesting experience to set straps inboards and forwards. Effective jibing on the Kombat is done with the front foot in the strap and with the straps inboard and forwards, you have a much better chance to keep the board planing and also keeping a good carve. The reason is not only that you are standing balancing the board better but also that there is more room to place you rear foot on the rail without ending up in a very narrow and difficult to balance stance.