I had the a7r3 as well for a short period of time. I found A9 to focus and hold better on a moving animal. More importantly with it 20 vs 10 fps you never miss any of the action shots. You then can pick the best where with the A7... you may have missed it. I had an a72 and A7s2 and the A9 is a far better camera. In instills a confidence in you that you will always capture that right shot. I feel the added cost was worth it.