Why is simplus good for a side sleeper? Is it because it's narrower than most FFMs? I'm a very active side sleeper and I might give this a try if it works really well for side sleeping

I have been trying a number of FFM and none seems to fit me. I'm thinking about trying AirFit F10. However, I also notice some reviewers say that it is an upgraded version of Quattro. For me, Quattro didn't fit well with my facial feature, causing leak below my chin. I wonder if anyone could tell me...