Hi Sam,
If you won't delete data from dso, there won't be a problem. if you receive the same records thru source, its overwrites the data. so no need to delete data from dso.
If your loading data from DSO to further then you can use delta dtp and choose data from chang log table.
When data source doesn't supports delta, then using dso before the info cube is advantage.
http://scn.sap.com/thread/3218124
Thanks