I would keep the X100 in your wedge, I tried going S400 and had the same issue as you, same kind of distance numbers
sorry haven’t read all of the thread in case this has been mentioned. The Mizuno wedge is likely has a flatter lie angle than your Titleist’s which may be causing the face to open slightly at strike. Get it checked if you plan to keep it. The shaft might be shorter too which would explain the swingweight difference.
The specialist wedges will spin a bit more, it’s why you see most people with a 46 degree Vokey. My last PW was an SM7 Vokey, I have the 620MB now bent to 48 for gapping.