Honestly its hard to say if the growth is only due to lighting. There is vey little that is completely constant in these systems. My experience is far from scientific. Maybe its safe to say, the split hasn't hurt anything.
One of the biggest reasons my growth is good, I believe, also has to do with flow. I am cranking 2300 gph through a 45 gallon tank (with closed loop on OM, power head, and return)...so its turning over 50 times per hour.