Hmm... You should sail the boat in those conditions.. No if's ands or buts... you will notice a big difference compared with your 6.0. Your pucker factor will vary.

The rig is not optimized for normal North American sailing seasons. (That is why Nacra introduced the first F18, with a taller stick in the NA market before dropping this idea with their F18 and Infusion lines to keep with Tiger in the USA market).

The appeal of the F18 class is multiple builders, good solid boats and lots of buoy class racing in a couple of regions in the USA and the ability to customize your sails for your mast and team weight..

The class would list performance in the 4 to 10 knot range well down the list of selling points. 12 knots and up... much different story.

Bottom Line.. you seem to weigh the BOAT more then CLASS RACING in your choices... Sail the boat in the conditions you normally see.

Your alternative would be a Nacra 20....

Always fun to search out and sail OPBs!