Most transection reagents recommend transfecting in serum reduced or serum free medium. There are some that are advertised to be equally as effective in the presence or absence of serum. I would be inclined to transfect serum-free to be on the safe side. Unfortunately the only way to prove anything is through testing. If this was going to become a model for transfection that would be done routinely, it might be worth investing the time. If the transfection is specific to a short-term project, it may not be worth the effort - just go serum free to reduce the number of variables. The cell line you are working with is relatively robust and should be able to take a period of serum free transfection fairly well.