vehicles with electronic trailer sway control

Several modern vehicles - including the Ford Explorer and Toyota Tacoma - are now claiming to be equipped with an electronic sway control system. Does anybody have experience with the effectiveness of these? Do they substitute for other sway control devices. We were led to believe that you absolutely had to have weight distribution hitches and/or mechanical sway control devices, but have these electronic systems rendered these unnecessary? Does anyone know for sure whether the Audi Q5 TDI has the electronic system? (We have been unable to ascertain this from Audi dealers.)