I have made a decision: ordered an NCX 9.0
The C2 8.5 I used so far works very nice, since this is a sail with lots of bottom power I expect the ncx will give me better top speed and upwind performance. When it gets a bit too much I can chance down to a 7.5.
I sail the big sails with a select freerace 42 cm by the way.
thanks for posting,