I am all for leveling the playing field at a national level, but to do so in an individual school is narrow minded, and I am not sure it happens. Grade boundaries are set at national level, so if a particular school restricts calculators to the base model then they are still competing nationally with schools who have the better equipment. Ultimately a decent calculator will not make a poor mathmatician into the next Fermat, but it does help a little to check work and work with more speed and confidence.