This is the threadstarter.
Monday I tried my IS127 with 7,0 and 46cm Drake Ready to Race DW fin. Wind was 13 m/s - 16 m/s. Mastfoot 2,5 cm behind centre. The board behaved very well and speed was occasionally well above 28 kt.
Struggle a little bit to get good angle upwind with this set-up. When going upwind in the chop, the board hammers against it, but the ride is not unpleasant. Going with the chop or with the chop from side, the board is just super.
All in all, this was a very positive experience. This board is really fantastic with sails from 7,0 to 9,5.