Yes, that has me puzzled too. Never had grain issues or more grain than normal with XP2. I rated it mostly at ISO 200 unless light fell to much and then would move my ASA/ISO dial to 400-800. Of course RezaLoghme uses 35mm and lab development I believe. Still, I wouldn't think grain should be an issue with either.
I also used it with my Hasselblad 500 way back then. Indeed, as 35mm film you can see the difference quite clearly,
