The iO Series 9 outperforms the Series 7 in motor torque (40 % higher per Wirecutter), offers premium haptic alerts, and uses a higher‑grade polymer for durability, making it the clear leader for tech‑savvy users. The Series 7 still provides solid AI feedback and a full week‑plus battery life at a lower price, suitable for those who want premium features without the top‑tier cost. Both share th...