Super to hear that you still can uphaul it easily.
Yes, I would also use only 7.8 and 8.8 on it.
Your low wind range 13/15 is very similar c/w mine on the 122.
Your high wind range I find quite high. In 22/25 knots I'm either on my IS87 or on a wave board. But anyway, it is nice to hear that it can handle this wind range. Even the flattest off-shore water will become choppy unless you stay very close to the shore or a dam, typcially a "speed strip".
IS87 / IS101 / IS122 / US147