I think it really depends on which RB or Vitamin you use... there are so many brands and options out there that you really can't make a blanket statement about either one. I had the opposite experience going from a highly recommended, expensive vitamin/mineral supplement to a ration balancer. My horse was barely growing any hoof (which was bad because he didn't have great hooves when I got him and not growing meant the farrier had very little to work with). Within a few weeks of switching, he was growing at a normal rate. When I compared the 2 options on FeedXL it was really obvious that he was very deficient in several areas on the vitamin.