PlaneSWING Training Aid - worth the investment?

I'd have one if I could sneak it into the house & hide it from the wife. Have had a couple of goes on an Explanar and it's a revelation. I've got a shallow, too inside backswing. When I went on it the first two feet of backswing felt perfectly natural. Then it felt as if the club was moving vertically upward. If I couldn't have seen the arc I would have sworn that's what I was doing. I was at the range this morning hitting irons badly when I remembered this, tried to simulate that feeling and immediately started to hit it better. Everyone should have a go, it's especially useful for "One Plane" swingers, i.e. people who swing the arms & shoulders on the same plane. Give one a trybif you get the chance, no need to own one, just remember the feeling of a correct swingpath.