I think having both is best.
The circ pump is great for 24 hour ozone injection, quietness, and possibly efficiency.
I still think it is a good idea to run the main pump at least for 15-60 minutes a day in order to stir up debris that the circ pump might otherwise not effect, and to keep water in the lines fresh.
My old Sundance, and new Caldera did/do both, and I feel it is part of my success in keeping the water clean with minimal chemicals.
One thing I don't like about Calderas implementation is that ozone injection is 100%. The Sundance would stop the ozone when the pumps were on (thinking someone was in the tub). The Caldera is better than the Sundance in that it has I think 13ft of tubing for the Ozone to do it's job. When the ozone was on in the Sundance, you could easily smell it. In the Caldera, the smell is much more subtle, but it is there. I wish Caldera disabeld the ozone when pumps were running...
jeff