I've heard and seen conflicting reports, and in some cases 25 was sharper/better than 100. I have quite a bit of Ektar 25 and Royal Gold 25 in the freezer if you want/need to try some. Also shot a lot back in the day and still have negs. Someday I will do a comparison. Ektar 100 is pretty good overall, I use it and don't really feel bad about not using the 25 much. 2 stops more speed is a nice plus, esp. with slower medium format lenses.