What would be the perceived negatives Dave? Any thoughts?
Well for starters the site talks about rowers not paddlers (rowers face the wrong way) and surely you would smash your knuckles on the change over. Plus throw the balance of the paddle out but would make it easy to hang up on the wall. The video really shows very little why it works. Looks difficult at the end of the stroke to feather the paddle plus it makes you pull the paddle way past your feet.
Last thing I would ever use in the surf your bottom hand is never in the same position , but at 49 GB pounds it's a bargain

The fact they keep using the word rower shows how little paddling experience they have.