Check out Revisiting the ROI of DITA by Sarah O’Keefe. Here is an excerpt:
This post is part of Scriptorium’s 20th anniversary celebration.
Back in 2011, I wrote a post on how to calculate the ROI of DITA.
Localization was a leading justification for DITA:
If you have localization in your workflow, you can probably justify the cost of DITA implementation….