Many of our customers are actually installing a larger system with the two-stage capabilities. This allows you to have a larger capacity system installed for the hot days when you have company which burdens your home with a heavy heat load a regular sized A/C system may not be able to handle. A two-stage A/C would then be able to handle the extra heat load by automatically switching to full capacity, and then stepping down to a low-stage for all the other times. Its basically like having two size air conditioners in one.