Hey, winter season is starting with us, time to chat again.
I have the impression that the IS110 is troubling a lot of people, including myself.
In your case mikerb, with your weight it seems pretty easy to me. Like yourself I'm not a PWA competition rider, but personally I like to ride the isonics a bit more powered up.
If I were you, I would keep the 127 and 107 and get rid of the 122. If you want to buy a 3rd board, go for the IS87. It's an amazing board with 6.x race sails. I'm 10kg heavier than you and I use the IS87 with 5.7 & 6.7 sails in +/- 20 knots average. When it are 24+conditions, I'm also on FSW stuff, unless I'm on a speed strip.
I think you should use your 7.0 & 7.8 on the IS107 and reserve the 8.6 for the 127 in the light winds.
Should be pretty straight forward. What are you doubting about ?