To be honest, take the Pioneer DJM-700 instead, it costs a bit more but jou get a great 4 channel?mixer.
I?don't like the build quality of the Behringer stuff.
But that's my opinion.
"it costs a bit more" are you sure? Because the DDM4000 costs in holland ? 369,- The DJM-700 costs in holland ? 939,- we aint talking about a "bit" more, but a lot
more then the DDM4000, the DJM costs 530 euro more then the DDM4000
The Behringer DDM4000 looks like a good mixer. and its a lot better then the Behriner DJX 700/750
I would say GO and check it out in the store, see it for your self about the choice of the Mixer.
I would suggest the Reloop RMX 40 DSP BlackFire because its the same price class
Good luck with findig the right mixer