DTM will use the RSID that you entered into the UI in the Staging / Production fields within the Configuration section of Adobe Analytics. DTM handles this by having the separate staging and production embed codes. Any site that is using the staging embed code will send data to the RSID you entered in to the Staging RSID section, and likewise any site using the production embed code will use the production RSID that was entered.
I'm having a similar issue -- once I review the link you provided is it accurate to say I will be able to see my DEV suite populated based on DTM settings and since I receive a nightly data file for my DEV suite -- anything tagged should be visible in this file as well, correct. It is just unclear whether we will see data fully in our DEV suite versus a move to Production.