I have a child in the Allen ppcd program and love it. My daughter has made significant progress in her speech just since January.
However, I have recently talked with a mom with 2 sons that qualified for the Frisco program. She sent one but not the other. The reason she didn't send one of them is because that particular program didn't offer one on one speech therapy, only group therapy. Her son needed one on one therapy and alot of it because of his specific speech problems. But her other son did not.
If you already know what your child needs just make sure the program offers it. If they do, you will probably be very happy with them. When I was doing my research, I learned that most private therapists don't have anything but good things to say about the school district programs and therapists. And it's free. But if you don't know what your child needs, you could have a separate evaluation from a private source to make sure that both sources line up with what they think your child needs. I did this and it gave me real peace of mind when I had to make the final decision on where to put my child.