Frosty Agreed, I have just purchansed a KDX and have ridden the XFS a bunch. I tried to buy either and the KDX happened to work out for me. Here are my thoughts from a get toghther of TXJ riders last year, most would agree. KDX had an 1100 PFP, XFS well tuned 850, very well dry pipe. this information is back flip only. For rolls I feel the XFS is easier, surf, not sure but xfs with long ride plate isnt bad. KDX I only rode once in surf, and it was set up for flat.
Xfs had a better trim set up IMO so this may negate some of this statement.
KDX:
Turns more centered
Lighter feeling
Lighter
not as much pop off same wave
More height
Less rotation
Carbon and nice build quality
XFS:
feels light in water, not so sure mid BF
Huge pop off same wave
less height, more rotation. Prob 15 to 25 deg more
Glass nice build quality
If you want to compare Carbon to carbon, this argument get more complex. Im strictly doing glass to carbon. In all honesty, i dont think you can go wrong either way. With skills either ski is a world class proven winner.