I'm also on the KS800 (65inch), and was very very close to buying a c9 this weekend. Ultimately, I decided to hold off for next year. I want the new TV for the features that will supported for Next Gen, but Next Gen is still a year off. Figured whatever deals I can get on the C9 right now, I can get on the C10 in a year from now. Plus, Since the Sony's have better image processing, I'd want to see what they bring to the table in terms of gaming optimization on their panels for 2020. If they are feature comparative (input lag, VRR, etc.) , I'd rather go with the Sony as it looks like the best of both worlds (LG Display + Sony Processing).
This is me right here except I have a 55" KS9000. Also was inclined on C9 or B9 but the deals weren't all that in France. Might as well for the whole package next year (PS5 + whatever tv matches and is available at a decent price).