Anecdotally, I was speaking with the dad of a boy that was on my sons' team last year. We've had several conversations, primarily over diabetes treatment.
I asked him how ACA was affecting his family practice. It's booming, he added a physician to handle the demand, but he doesn't take Medicaid or ACA. Red tape and low reimbursement rates were the two main factors.
He sees a day in the near future where doctors will be mandated to see Medicaid/ACA patients as a condition of licensing.