I have looked at this before and would really like to try it myself. I think it would be a really effective tool for learning that feel of having your hands ahead of the ball. I have the tour striker, but I think the DST would be even more effective.
One thing that surprised me is the guy's explanation about why he created the club. At about the one minute mark of his video he said that he designed this aid because he noticed in all the photos of great ball-strikers that at impact the club is bent backward. What?!?! I don't know whether he says this as a sales pitch to make the concept consumable to the average viewer, but he is promoting a myth that too many amateurs believe: that the club can come into impact bent backward. It doesn't (and can't unless you are using the Whippy Tempomaster or you are one of those long-drive behemoths swinging a REALLY soft shaft).
The club may begin to flex backward upon impact due to the force of impact and will do so in an even more pronounced way when the club makes impact with the turf (ideally about 3 inches ahead of the ball), but if there is any flex to the shaft coming into impact it is a forward flex. So, if this guy really designed the DST to mimic the "backwards bending" of the club, he fluked onto it. A good ball-striker leads the swing with his/her hands and the club has a forward lean coming into impact as a result. The DST forces the player into this position and eliminates the flip. Period. It has NOTHING to do with imitating the flex of the club at impact.
I suspect this guy meant to say the backward lean of the club, not backward bending of the club.