Here is one of the two newest sirens installed in Lewisville. It was installed around March 2016. This siren running the 560Hz tone seems to carry much further than the older R4s running the 465Hz tone. It was definitely impressive. During the test, I noticed that when the siren reaches the point in oscillation where it pauses before switching direction, there was a much longer delay than normal before it resumed oscillation.
https://www.youtube.com/watch?v=9MEndBSdRmY