Hi Cal,
The 100mm/3.5 seems to be relatively less often found for sale. I also have a second body with a 100/3.5. Dante Stella has a nice write-up on this ystem. It is there where I read about the "rarity" of the 100/3.5. Many years ago, I paid $500 for the G690BL plus the 100/3.5AE. The AE offers me aperture priority and also AE flash.
I would expect the regular 100/3.5 to be as sharp.