I'm guessing the difference you think you taste is mostly psychological. Free range only means that the chickens had access to the outside. That means they could still be raised in a warehouse that just has one small door that leads to a tiny outside area.
That's only the case if you don't actually know the farmer producing the chickens. The ones I am thinking about live out side most of the day and eat a lot of insects. They are often non standard breeds so it's a significant age, diet, exercise, and genetic difference and not just a meaningless 'feel good' label.
PS: IMO, there is alot of good things about cooking with factory farm chickens, but novelty is also nice.
The free range certification doesn't mean much. But I the difference between a corn diet and the natural meat diet of chickens causes a flavor difference in my opinion.
However, you could probably just create a new flavor(s) and only apply it to nutritious foods.