I think this question would be better phrased as, "How much of a pay or benefits cut would you be willing to take in order to work for a socially conscious employer?"

Studies have been done along these lines measuring consumer willingness to pay for eco-conscious products. Not surprisingly, it's a question of how much the premium is. See http://www.mckinsey.com/insights/manufacturing/how_much_will...

I imagine similar studies have been done on organic food.

Of course many of these studies go off what people say, and really we need to measure in all of these cases what people actually do when confronted with the actual choice.