> If I'm remembering correctly, Walter Isaacson's Einstein biography tended towards says that she didn't truly contribute much to any of the work he did around that time....

I'm not sure how much credence I'd put in such an assertion given that Einstein himself wrote in a letter to Mileva:

> “When I read Helmholtz for the first time, it seemed so odd that you were not at my side and today, this is not getting better. I find the work we do together very good, healing and also easier.”

Emphasis added by me.

Having not read the book, Isaacson might have some additional evidence and insights I'm not aware of, but who knows?