I've got a Xone DX and I'm running Traktor on internal mode.
I had a quick play about last night with itch just to see how it compares with Traktor Pro. Anyway I noticed that some of the effects in itch such as the echo are set in a way when you kill the fader the echo fades out. I've tried to do this in Traktor but because the effect is selected to one of the channels as soon as I kill the fader everything stops. I used to do this effect on my DJM800 and would really like it back. Does anyone know how to recreate this in Traktor. If you understand what I'm getting at.

The behavior you are looking for has to do with insert vs. send effects. Traktor Pro did not remove the functionality you want, it's just only available when you're using the delay effect as a 'send' effect. AFAIK send fx are only available in external mode, so you need an outboard mixer (and some cables) to make it work. The theory behind it - as was already mentioned - is that when fx are in insert mode, they are in-line with and affected by the position of the channel faders/cross fader. When they are in send mode, the wet return signal is not choked by the faders. Think of it as a totally separate sound stream. In that case, when you close the fader, you just shut off the signal being fed to the fx unit, but you are not cutting off the delay tail.