RE: My board: Isonic 105 dram
The last sessions I used even the 6.9 in low wind conditions. (12-14 knots with 18knots gusts)
In the low conditions it is a bit less comfortable.
In the gusts you get really an super acceleration compared to the bigger sailssizes.
Topspeeds just increases a lot when planning in gusts.
I think for crosswind cruising a bigger sailsize is nice for keeping pressure.
7.5 is best low wind sailsize. But my bro is thinking the same... he is 100 kg, I am 80kg... so that is why I use at the moment 6.9
I sold my 8.3, I just took the only in very low wind <14kn gusts... what resulted in very frustated sessions where I was just very slowly planning 50% of the time