Seven Months later!
Here is what happened visually. The steel wool pad isolated from the car body looked to be in better shape while the pad directly connected to the body looked positively rusty.
BUT when these two pads were weighed the isolated pad was heavier.
What this means: The isolated pad (attached with plastic bolt) rusted more. (There were more oxygen molecules attached to the iron thus making the pad heavier.)
Conclusion: (Much to my amazement) The electronic rustproofing device did inhibit rust, but only slightly.
Other observations. The car seemed to continue to rust as there was a small rust spot next to the rear window in November which has grown larger over the past six months. The difference in weight between the two pads was minor and could have been due to other factors such as dirt or the location of the pads under the vehicle (One pad was mounted a bit higher up due to space restrictions.)
My opinion: All in all the electronic rustproofing is an expensive option with little observable impact. But it may have had some effect in reducing rust.