I notice a fairly significant difference in support between the different style shimano pedals when using xc-9 s-phyre shoes. Mostly I notice this when cornering hard and landing drops. While cornering I feel like the outsides of my feet want to roll off the M9100’s vs. my M8120’s causing some ankle discomfort. When landing drops the impact also causes ankle discomfort in 9100’s.
For everyday trail riding and training I ride the 8120’s but for xc races and gravel I put the 9100’s on. I also do this because I’ve had to warranty two pairs of XTR 9100 pedals. They don’t seem to last long for me and I worry Shimano won’t warranty them forever.