Hi Dan,
You are getting great speeds out of the NCX's.

What mast are you running on your 6.5m NCX? I see the recommended mast is 430 although the luff length is 462. At the moment (as I have a 5.0 and 5.7m blades) I'm using my Gorilla 430 mast. I was thinking of getting a 460 90% SDM mast so I could use it on a future purchase of a 7.5m NCX or turbo (haven't decided). I'm 88kg and use it on a Starboard Atomic IQ 110.
Thanks Dean.