Having a manual over-ride switch, however it's done, is a great thing when sat in traffic jams. If I get stuck in heavy traffic, as soon as I see the temp gauge get above 90 I hit the switch and can relax knowing that I'm not going to be left in the breakdown lane with steam pouring out of the rear hatch.
Before I fitted the switch, the guage would get to 100 before the fans kicked in which made me very nervous. Sat in slow moving or stopped traffic, the coolant doesn't take long to get from 100 to 120 if the otter switch doesn't click in. Sat wondering whether your engine is going to over heat or not isn't a good feeling, especially in Aussie weather.
Living in the land down-under