In my current project I am working with rather large DataContracts. Ie. a class containing 10-12 other classes.

In such a complex DataContract it is very tempting to make a partial class and implement some interfaces on these contained classes, in order to decouple the business from the DC.

However this is not possible since the channels in WCF are very sensitive to this kind of structures.

So my recommendation is to keep the DataContract as simple as possible and make adpater classes instead.