For those interested, as I am someone with actual hands on experience with this product..it works well, with minimal tension on the top wheel.
The bottom tension wheel is doing as it should, adding tension. the top tension wheel is holding the top chain in place, feeding it into the motor at an optimal angle, without any noticeable extreme pressure on the top wheel... certainly less tension on the top than bottom, and not a cause of concern.
Edit: actual hands on with this product, you would realise the bottom wheel is not pulled up as tight as it normally would be. Therefore the top is not tense as it would be, allowing it to adjust over the top wheel as needed. Your assumptions are based on how this system normally works with one wheel.
I dont have the bottom tensioner overly tight to begin with... there is some small amount of slack overall which allows the chain to rotate smoothly without too much tension, but of course not too much slack to jump the wheel.
After roughly 30 miles of riding, it is the smoothest tensioner setup I've had thus far, and would recommend a try to those with similar issues. I dont think they would be selling kits with this method if it didn't offer some benefit....but if it fails in the future, I will return and update.