I response to your question, I would have to admit to being the type of sailor that Ian identifies as preferring the smaller board that rides closer to the water. Of course much of this has to do with my lighter weight and smaller size (70-72kgs x 1.73m), but even a number of years ago when I was heavier (86-88kgs), I still felt the same. Also, all my sailing is done in the ocean where the running swell can differ from the more immediate wind generated chop.
Regarding my experience with the iS101, I have to be frank and admit that I haven't riden it. All my slalom boards are customs made by Mike Zajicek (Mike's Lab), but I'd think that you'd agree that recommending boards other than Starboards here wouldn't be too appropriate. But to give you some idea of my board spacing, the volumes are (noted as approximates) 85, 100 and 120 liters, and my widest board (the 100 liter) is 61cms. The 100 liter board has a very similar sail range to the iS101, but it's more skewed to the 5.0-7.5 range. With a 7.0, its super sweet across the full range of the sail, even the real light side of the spectrum.
Although many good points have been raised contrasting the iS101 and iS111, I would hang tough with the smaller of the two boards as the best choice. However, if you were targeting a one board solution, the iS111 would probably offer a more well rounded selection.