They do NOT work well as a spinner.
They are digital devices, and send keypresses, rather than optical data.
They also have no weight to the base, so you would have to glue the thing down to get it to stay in place while you spin it.
There is also some kind of friction device inside, so that they turn more like a volume knob on your stereo, rather than a spinner of any kind.
I do HAVE one on my cab, but only because I didn't want to hack my Mac to get a remote power on.
I use the PowerMate solely for turning on the computer.