Wayne, maybe Steve was talking about the different tones not just the volume. I also have the Primos Growl and it's a nice call as well.
Speaking of deer vocalizations, many moons ago I went to a seminar that featured Bob McGuire and Butch Todd that I found very interesting. I think Bob was one of the first to start studying deer vocalizations back then. His book Bowhunting October Whitetails is still one of the best reads ever published.IMO
Often wonder whatever happened to him? Maybe Mike knows!