The answer to your question is that you can use the Xone DB2 with all of its functionality, you just need to buy an external sound card and some sort of controller. Native Instruments have the X1 controller and Allen & Heath just released the K2. I personally use a XONE 2D, which has an 8 channel sound card and is also a Midi controller. Either way, you'll have to do your research on which suits you, but the K2 and X1 are pretty nice (and yes, you can still control pitch, queues, loops etc). You will just have to look into a good sound card to go with this.
Then, you go from your laptop via USB into the sound card, which breaks the signal out into an input for your mixer (usually RCA, for each channel you have in traktor to one channel on the mixer). From there you then mix normally via your Analogue mixer and go out to your speakers/amp. So essentially, it's mixing post digital. Just make sure you set Traktor so it knows you are mixing externally. There is an option to select your sound card and then select external mixer, it's very easy to do.
One advantage of this that all of the people who were badmouthing you failed to mention, is that when you play out, you don't need to take your massive mixer-controller with you to clubs. You are used to the layout of a mixer and you just need to bring your sound card and small controller with you and plug it into the clubs mixer. Also, if you decide to get vinyl at home you can still add it in.
There is nothing wrong with this setup, it's just another way of doing the exact same thing. That is mixing tunes. There's nothing wrong with having a quality mixer. The feel and ergonimics of a AH DB2 are far superior to a Kontrol S2 or S4, so if you can afford to do it, why not? You'll more than likely be mixing in clubs on an analog mixer, so definitely have your home setup in the same way.