I was invited to a preview showing of the frame when it first came out, and got to hit with it. You could adjust tension by turning the knob, and you could make it play quite differently. I feel it would be illegal today because of this.
BTW, the racquets we used already had quite noticeable damage to the grommets from being adjusted so much: many were cracked or broken away from the frame. I think this thing would've been a pain in the neck to maintain.
Remember: just because you could adjust the tension didn't mean the strings couldn't go dead, so you would still have to restring, even if a little less often.