M.J.
I have never heard of Learning RX. I'm assuming it's a chain deal like Brain Balance? Did your child's psychiatrist recommend it? Be leery of any places that seem too upbeat ("We see dramatic improvement!") or ones that claim nutrition will help ADHD (it's helpful in general, though). Make sure a medical professional oversees the program, not just some franchisee who happened to pay enough to get the franchise in that market.
Our son started behavioral therapy at four and is 10 now. We go together and discuss the challenges he's facing at the time. It's been really valuable, in conjunction with medication.
For our son, the best "wow" results by far have been with medication. The therapy is essential because it gives us coping strategies, but it doesn't change what's wrong in our son's brain. The therapy didn't start working, actually, until we started medication and he had the ability to follow through with what was learned.