I can't find the study, but a South American government(I forgot which country) had the same fears. They wanted better employees and they were afraid if they paid them too much they would get people primarily interested in the money and not the job. But they decided to try it anyway, and lo and behold they were surprised to find the higher played employees were not only better employees but also more motivated intrinsically by the job. I would be curious to find any evidence to the contrary.

I try to be very suspicious when my views about how the world works line up with some way that I'm benefited monetarily. For instance it's very hard for me to have a clear and accurate opinion of oursourcing and h1-b's.