I'm not sure specifically about the CHIRP but regular sonar is rated for 1500 feet. With DI or SI your depth is much lower since the signal isn't as powerful.
I'm thinking this is like the Humminbird Helix "switchfire" sonar. From what I read its a higher ping rate so you get much more detail and a faster refresh rate on the screen. I've seen most people turn on the switchfire when their jigging below their boat so they can see the depth of their jig on the screen, regular sonar wont show that much detail. On the Helix 7 you can select between sonar and switchfire. I've included a picture from my Helix 7 box, I'll have better info after I use it for the first time tomorrow
I could also be completely off on what CHIRP is