There is a new study from West Michigan (pdf), by Leslie A. Muller, Paul Isely, & Adelin Levin, based on questionnaire responses. I would take this with a grain of salt, but still it is useful information to throw into the pot. Here is one excerpt:
Many firms have decided however to minimize their exposure to ACA costs by limiting the employees that must be covered. Questions 14a – 14c show that 36 percent of firms are considering (or using) temporary workers, 44 percent are considering or have reduced/limited hiring over the next 12 months, and 51 percent are considering or have already reduced/limited hours so that the employee is considered part-time.
You may find the tables on the last few pages of the paper of interest. The results are based on fewer than 180 observations and presumably involve some selection bias as well.
The pointer is from W.E. Heasley.