So what's the total travel?
I can't remember what the advertised travel of the F800 was standard, but I do remember using the cable tie measuring process and establishing that the advertised travel was a bit more generous than actual. Especially so after the Ohlins 0.55 springs went in.
having 300mm of travel now is magic. With proper damping it works so much better across all trail types.
I had the Showa forks rebuilt for my 650, with fast hard trail work as a reference. Plenty of air time was factored in. This has translated very well to the slightly heavier 800. Even with lighter spring rates than the Ohlins springs I had, the Showas work so much better that there really is no comparison.
I thought about the Xchallenge forks, but after talking to a guy that races one I was put off the idea. He reckoned I was better off looking at a complete swap. I'm glad I did now. There were some slight engineering glitches, but nothing insurmountable.