I'm all about paying above market rates, you get what you pay for and it's not a linear scale, probably more like an activation function.

There is an interesting idea that seems to be working well. That is salary transparency. Everyone in the company knows how much everyone else makes. It instantly removes gender / race / negotiation skills as a difference maker. Geography seems like it would benefit, and that some amount of cost of living adjustment ought to be incorporated, though perhaps how you do this encourages behavior in some direction.