I now have 4 or 5 sessions on the surf tracker with integrated spreader bar pad mounted to a Mystic Warrior. Used it in swells (TT), surf (mutuant), boosting (TT), and hydrofoiling.
Pros: The hook goes from side to side seamlessly and without notice. It just works. But the real bonus for me over the rope and sliding bar systems is that it doesn't allow the hook to move vertically. For me, that is great because I like to jump a lot and keeping the chicken loop down keeps the bar down which keeps the harness down better. I feel smoother on toeside. My center of pull is still in the middle and doesn't move.
Cons: The attachment to close the harness blows. To have it open enough to get it on I then have to pull the straps to tighten down the harness afterwords. Maybe not so bad bare handed, but in neoprene gloves it double blows. Of course, I've never found a really great system from any brand. At best they are good.
Unknown: Durability and longevity.
We sell Cabrinha and NP but I pull no punches. We won't sell stuff that is going to end up as a return item and scare off a return customer. At this point, we will order them for someone who wants one, but we are not stocking them until we are sure about the durability and others try the closure/buckle thingy and render their verdict.
If it lasts and the buckle thing is OK with you, you might really never go back to another hook.
BTW, I have been riding a custom Ride Engine harness for 3 years. In my mind the Engine thing is about the stiff back. I'm not a fan of the rope hook thing.