People complain about Hot 97's lack of playlist diversity as if hip-hop radio is supposed to be the only station not driven by hits. Truth is most people only listen to the radio in 45 minute spurts- on their lunch break, during the drive home, or during a workout. So, for that space of time a radio programmer better play the latest and best music, then repeat those songs again in the next hour. This doesn't leave much room for music outside of the Top 40.
Now Hot 97 did something a few years ago that's different than most radio stations, hip-hop or not. They handed over their after midnight time slots to the most popular mixtape DJ's in New York. This was a genius move, I think.
Unlike their regualr programming, Hot 97 let's the mixtape DJ's play whatever they want. DJ Clue and Whoo Kid bump song after song from their crews (Desert Storm and G-Unit), and Kay Slay allows the occasional cuss-word to slide. The mixtape DJ's break future hits that haven't made it on the charts yet, unoffical remixes that you would never hear, and exclusive freestyles from artists underground and mainstream.
For Hot 97 this is the best of both worlds. Funkmaster Flex gets dogged by payola rumors, yet the mixtape DJ's do it all the time and are popular for it. And while the Gray Album had lawyers trying to stop it from getting played, DJ Green Lantern does similiar unauthorized mash-ups every week.