It will depend on your weight and skills. If light weight, not much difference (± 1 knot). If heavy weight, gain will become more significant with the largest width.
Active pumping skills is mandatory. It is easier to find the correct nose pitch to start and sustain the planing with the longer UltraSonic 147 as compared to a large iSonic or a Formula which are a bit shorter.
As for me with an 11 m2 sail and 65 kg weight, planing as early as 7 knots with iSonic 117 Wide or UltraSonic 147. With a 100 cm wide Formula, planing as low as 6 knots.