Using the jacoco java.agent is pretty simple to set up and generates a coverage report file without affecting performances.
We could think about starting JBDS with this java.agent and consume the Jacoco report files to get "technical" usage report.

Same could apply to JBoss tools by using p2 touchpoint to modify eclipse.ini when installing an IU: http://pweclipse.blogspot.com/2012/02/p2-can-update-your-eclipseini.html