Hi everyone,
This is a question with its own answer. 🙂 If you are producing large PDF documents and you mark revised content with change bars, the following utility can make it easier to review the changes:
https://github.com/chrispy-snps/pdf-annotate-change-bars
The PDF can be created by any tool, not just FrameMaker. The requirements are that the background color around the change bars be a solid color, and that no other obstructions (headers/footers) intersect where a change bar could be.

Hopefully someone finds this useful!
- Chris