Political scientist John Sides has contributed an interesting guest post to FiveThirtyEight, in which he reviews the evidence that social class influences the way Congresspeople vote. In particular, Congresspeople are unlikely to come from working-class backgrounds, and class seems to affect voting at the individual level. If Congress had the same mix of class backgrounds as the general American public, they would in general be slightly more liberal.
My first reaction was: I wonder how much of this reflects IQ. Intelligence makes people think like economists and also increases people’s income and probably shifts class background toward mentally intensive occupations.
My second reaction was: Assuming the result stands, do we want Congress to reflect the same background as the American public? Should everyone be represented equally? It’s not obvious to me that they ought to. I’m on record here as supporting limiting in some way the right of government employees and contractors to vote. Even if you don’t share my libertarian proclivities on public policy, however, a slightly upper-class-tilted public policy regime might be desirable for straightforward reasons of stability. In a pure democracy that is strictly responsive to the median voter, businesspeople and professionals might become alienated from democracy itself. That may sound like a bit of a stretch for the United States, but not for many countries around the world where upper-class opposition to democracy has entrenched electoral fraud, clientelism, or military supervision of civilian authority.
PILEUS 
I’ve always understood that one of best features of representative democracy, such as we have in the United States, is that the elected representatives are free to advocate, vote, and legislate according to what they think is best for their constituents and the country, which, hopefully, is one and the same. Not to argue that this is how it operates in practice. I don’t think having a congressional delegation whose demographics match those of the voting public would undermine, or enhance, this feature of our system. I certainly think that some artificial and mandated mix of class representatives in Congress is a very bad idea.
As an aside, I like the idea of disallowing or limiting the voting rights of government employees and contractors, including limitations on their political speech, i.e.; political campaign monetary contributions.
“Should everyone be represented equally?”
In a legitimate polity, I think the answer is quite obviously “yes, everyone should be represented equally.” This does not mean, however, that everyone should be represented according to socio-economic class. Rather, everyone ought to be represented equally according to those traits/issues each person thinks is important.