We went last September with free dining, and the crowds were still bad, and the heat and humidity was sometimes unbearable. We couldn't wait to get to our cool room in the afternoons and evenings. With a baby, I would say not to try the heat and humidity. Free dining is ok, but it is not worth the heat and crowds. People say they don't take kids out of school but there were lots of school-age kids when we were there. I told my DH about the free dining last night and when I told him the dates he said "we'll just pay for our food, then." Last September we declared we'd never go back when it was hot (we live in the South so we're use to the heat and humidity, but not at WDW-too draining of energy!)
Hope this helps!!