@hilly smaller tail may work but not in the same surf design as the FT range. It would not be possible at my weight to easily use a RS650 so out of the question.
@anyboard not sure it's my experience or technique, 2 years winging, heel/toe side tacks etc, 2 years advanced kite foiler, 20+ years advanced kiter twintip, and yacht sailer/racer. I can go faster if I bear away from the wind, but thats not how you race right, well a few legs will be like in a windward-leeward course but the others will be beating upwind, and racing is just like as some say mowing the lawn, but typically I beat upwind and carve the bumps downwind. Good idea trying other gear. The RS1150 is fine from 15kn for me wing power only with 6.5m wing, be much lower wind for you as you are 20+ kgs lighter than me.
I thought it weird the gap between RS650 and RS1000 and was hoping the RS850 was like the CAB800/1000, but I was disappointed when the release came as the RS850 doesn't even belong in the RS range, should be the HA range. So there is still a gap in the RS range between RS650 and RS1000. Brands from my experience, with 3 now, do very funny things indeed. Others bash axis for quality etc (never ridden/owned them) but at least axis does a foil in every range to cater for all weight classes.
When I say flat water, it's botany bay so it doesn't stay flat for long, once wind gets past 17-18kn, becomes 1-3ft messy wind, tide chop and generating board speed in this sea state is near impossible.
I think all wings have a cruising speed range right, just like planes, they design their wings for a particular cruising speed for fuel efficiency, so the same would be true for foils. I'd probably say that GF are designed for the wave speed on maui, makes sense right

to cruise on the wave, and if designed for a faster cruising speed they will outrun the wave.
I think from my experience that this is the cruising speed of GF wings, unless my fenix is wrong.
Could be to do with the mast or as the new buzz word is right now the `foil section`, the foil, or the tail. Easiest for me is to try a different tail outside of GF surf tail offerings.
It'd be interesting to see the stats of other riders
wing foiling only with
no wave assist at all to see if I'm right or not.
I started on Moses, then Armstrong and I think these were faster average speeds for sure but this was pre my fenix so no empirical evidence to back that up.