Frankly, the case for DTOs is well and truly closed – take a look at Martin Fowler’s entry for a good description of the pattern from his book Patterns of Enterprise Application Architecture. There’s a heap of other references from a simple Google search.

In this light, I was recently directed to a new assembler library by Rob Monie that he described on Back to Front. Its very easy to use and allows you to manage the process of traversing the object graph quite easily relying on convention over configuration techniques. It goes a long way to taking most of the tedioum of providing an assembler and transformation mechanism for your domain and DTO objects. The project is free and open source on Google Code. Definately worth a look.