I have the Logitech driving force wheel and I have just found the power assisted steering setting and it was off .Does it make a lot of difference having it switched on ?
No, It's not much of an aid. I think it makes your wheel feel like crap.
If ffb is too much for you to control, you could turn it on. I have used it on my x2010 a long time ago, the ffb used to be way too strong for that particular car. Don't drive that car at all anymore.
From my memory of trying it (hated it), it was a assist, it assisted with fast movement of the wheel, the FFB would let up resistance when the resistance was high, assisting you in quick wheel movement to catch slides etc.
But it wont make you any faster like SRF does or anything.
It is switching off the feeedback motors when you turn faster than certain speed defined for this function, nothing else. It was must with old muscularly geared Driving Force Pro but with G25 it's unnecessary feature that deletes all the feel in the wheel...