We primarily pass the client side values to our backend services who use them in the server side calls. This ensures our client side analytics implementation uses the same values as Target. This can be done by extracting ECID, AAM Blob and Location Hint from the AMCV cookie.
I don't know Pedro but he has written some great stuff about server side as well that we found while doing our implementation. I think you'll also find them valuable:
We are exploring ways to do this in the App where cookies are not as transferrable.