Hi Carlos
The interesting point in your question is deletion of propagation layer.
In general this layer is the one which consolidates the data from various source and often used as a source of data for future developments and outbound interfaces due to several reasons.
Thus it is recommended (Not Mandatory) to have DSO's before loading to cube as if required its easier to make lookups on data in DSO compared to the data in infocube.
However please mention the pain point driving for analysis of design change, this would help to make more precise comments.
Ashish