Never ever hold a powered steering rack on full lock or you will damage it. I didn't notice a soft whine from the Powershift in the S-Max when I tested it, nor in two Focus, nor in a Mondeo. I was driving Hyundai's and Renault’s latest dual clutch gearboxes recently, and no whine from them either. But it has always been the case that one apparently identical transmission may while a bit, while another doesn't. This does not necessarily lead to disaster. Happily no reports of failures of Powershift boxes at all so far, and they have been around for more than three years.