RE: NP Saber or Excess as biggest sail on Kombat97?
Saber is great for blasting and freestyle à la supercross, but forget it for true waveriding. Excess is a good match for blasting, freestyling and waveriding, i.e., more in line with the Kombat program and with what you want to do infact.
The tail of Kombat 95 and 97 is pretty wide, so my guess is that an Excess 6.9 should be fine with your 75 kg. The tail of Kombat 86 might be a bit too narrow for your weight with such a large sail, however : sail size of 6.2 is fine with K86 and a 80 kg rider pal (he tried my board with his Search 6.2 sail and loves it).
I've previously used a Carve 111 2001 with Jet 6.9, NR 6.2 and NR 5.4 sails. The Kombat 95 felt as large as my Carve 111 during transition/manoeuver for my taste whereas the Kombat 86 felt much more lively underfoot for my light weight. The tail of Kombat 86 is large enough for my weight and 6.9 sail; that of Kombat 79 is way too narrow with such a big sail (NR 6.2 is still fine with a 28 cm crossover fin). The heavier you are, the less efficient a board can become to put sails larger than specs.