Aristotle Was Never A Middle Manager
Both Rawls and Cohen make reference to the Aristotelian Principle in various contexts. Rawls touches on it in his discussion of the good1 in support of the contention that enjoyment of life is linked to the maximization of a person's capabilities. I thought that was a debateable contention but it seemed like a small matter at the time. Then Cohen comes along and uses the Aristotelian Principle as a justification for paying the talented rich less2, a major conclusion which merits a response.
The essential idea is that the employment enjoyed by the talented rich is inherently more self-fulfilling/desireable by virtue of the fact that it allows them to fully excercise their faculties. To which I say "Ummm... no". That assertion is so self-evidently wrong that I wonder if either Rawls or Cohen had much exposure to life in corporate America? The work of the talented rich may require the deployment of a wide range of faculties at a high level, but that doesn't automatically equate into work which is enjoyable.
For example, consider the role of yours truly: I'm an engineering manager with a focus on IT operations. My job involves such things as managing system engineers, doing risk analysis/mitigation, and promoting IT cost containment. It's a pretty specialized role, and there aren't a whole lot of people like me running around, so I get paid pretty well for the work I do. A lot of my time is spent fighting bureaucratic inertia and general stupidity; when I'm actually excercising my skills is usually on something like activity-based costing for some product or goal-setting for my direct reports. Doing those things well requires the excercise of a broad range of skills, but none of it is terribly fulfilling. Every one-in-awhile I get to see a system which I helped architect come together, but such instances are few and far between. Given my druthers I'd rather be teaching martial arts, but such jobs just don't pay very well.
Furthermore, positions held by the talented rich generally involve more responsibility in the sense that if something goes South it's the talented rich who will be called to account. Far from being inherently desirable such positions lead to increased stress. I suspect that a lot more high-paying jobs meet Cohen's "special burden" than he seems to anticipate.
In any case the idea that something is rewarding simply because it requires the excercise of highly-developed skills is simply false. People will develop skills that they don't find intrinsically rewarding because such skills can be extrinsically rewarding. Or, bluntly, I can make bank doing IT even though I don't enjoy it very much.
1 A Theory of Justice, pp. 426 - 427
2 Rescuing Equality, footnote 50, p. 107