Purple fringe on the 85mm is the same if you also shoot at f2.0. Shouldn't penalize the 85mm because it opens wider.
Maybe i had a poor copy but i could definitely see a difference when i shot the same scene with both lenses wide open.
For me its a focal length issue. I felt 85 was too close to 50mm, but too long as a walk around lens, whereas 100mm is far enough away from 50mm to make using both worth while, especially if i needed longer reach, and it can cover a bit longer than my 24-70 without having to use my 70-200.
On FF i prefer it to 50mm as a walk around lens.