I have both a 90s and the 100 and frankly i like the 90 better. Just old fashion; as i like to change the aperture at the lens. So from my point of view you are not missing much by by passing on the 100.
Can you find someplace that will let you run a roll of film with each to see how it handles in the field? I also felt that, that is the true test, how does it feel with actual shooting than just handling in the shop.