I can see merits to the product. This would have been real handy on my Pokagon hunt last year. I went in with my Summit climber and pulled a game cart behind me. Combining the two would have been cool. I think if I hunted a ton of public land I'd probably invest in a product like this.
As to blood on your stand and seat. I use a net seat system for my Summit that I bought years ago that is a HUGE improvement over the standard seating. So a simple hose the stand off with water and maybe a stiff brush would be good enough to remove any blood.
I hunt private land 99.9% of the time where I can get a truck, ATV, or take the time to get my game cart back after the hunt so I really don't need this product. But if I hunted public land I think I'd buy it.
Cool product and one of those "why didn't I think of that?" ideas.