It's highly individual and specific to the child, institution, and teacher(s) at a specific point in time. We won't be able to tell you the "right" decision, because there probably exists a range of options that would be suitable to varying degrees and various aspects of your DDs development. But you already knew that!
A two year skip in a single subject at 10 has the benefit of being easily reversible and minimally disruptive for your DD, because she will be in the same building for all classes and with her age peers for the vast majority of her time. She likely has the executive function and social skills required to blend into a class of children 2 years older than her, and you have been assured that the academics would still be easy for her. Personally, I would consider it seriously.
