My question is why are you worried about the signal speed, I have a Futaba 3PK and when I used it on the HRS mode (this was with the HRS receiver) I could not tell a difference between them, The speeds that you are worried about are so fast that the response time differences are so small that I don't really think you could tell a difference. I would think that servo speed would be more important than receiver speed would be. The differences in the speed of the different servos are quite large and very noticeable. Maybe you could explain why you want a AM radio with "faster" response time...