The DJM 900 is a mayor step up from the DJM 800 soundwise. I'm not sure about the phono pre amps, but some external ones will take care of that.
If you're the only one playing at the club, then you might consider another mixer. If the mixer is being used my more DJ's, yeah, take the DJM 900 its the industry standard after all.
Technics SL1210mk2s and a Freevox DJ CLUB