Hi Pat,
I have power steering and hydrostatic transmission on my tractor. But with a spinner added, you clutch the ball of the spinner instead of holding the steering wheel. It is a very efficient way to turn a steering wheel and fast. You can spin the wheel lock to lock probably 3 times faster. That means you can turn faster, (with one hand doing the manuvering and the other working the FEL), with only one hand. Backing up and turning is a breeze, since it is easy to clutch the ball and turn, while twisted around looking backward and the other arm hangs on and supports you.
I would say get one and try it out. I have not had the problem of the knob being wrenched from my hands. Over potholy ground, I go slow...and have not felt the need to join the tractor racing association.