I never compare this 2 boards, on is a Formula and the other a slalom, so completly different programme.
The Formula must plane more quickly, but the iSonic 150 will be more easier to get plaining but also faster on the reach.
The Formula is a race machine for up wind and donwind or the iSonic is for reaching. But this iSonic will be good but less up wind.
Hope this help
All the best