As an official local guide who has been working in Florence and its province for more than 12 years, I would like to suggest the usage of head sets and radio for guided tours with more than 8 persons. In this way I can provide a much better service in museums and churches, but even be much more helpful walking through the city by advising and anticipating informations. Florence is almost always a very busy city and some museums might be very crowded even during low season.