2TECHSKIER:
I faced a similar issue with my i.SL Chips which came with the CP13 carve plate and not the adjustable railflex setup. I asked JBotti to check with Harald/Diana at a camp he was attending because they have a lot of experience with Head skis, and their response was that they always use Railflex skis in the +15 position (which on my older iC160's and the newer iM77's was very close to BOF/CRS), but that they recommended the factory position on skis with the CP13 plate. In my case, the default location for the i.SL chips was 15-18 mm behind the BOF location. I went ahead and used the skis in the default location and haven't regretted it or had any problems with turn initiation or balance. One of my theories is that the plate better distributes the pressure, and that as the ski bends the shape of the front of the plate and the rubber bumper underneath actually compresses and exert more pressure forward on the ski than when the ski is not bent.
Also, I haven't read or heard anything by any of the people skiing on SuperShapes indicating that they have done anything other than ski them in the factory default location.