I was reading a blog about election surveys using Mturk and ended up posting a fairly long comment in response to the authors.
The blog post did not focus on payment, but payment was a relevant issue in regards to results.
This is the link - The Monkey Cage
As you can see, the focus is on the election survey results, not payment. But from the conclusions drawn, they did not get a representative sample of workers on Mturk because of the low payment and therefore had skewed results.
Hopefully you have seen from previous posts that there are high quality workers on Mturk who will give 110% to any requester who offers fair pay.
Take a look at the post and give your input.