Thanks a lot Martin!
As a result, attached is the EARL report.
For reproducibility, it was obtained:
Using profile v20: http://ns.inria.fr/grddl/rdfa/2008/08/07/
Included in the service http://transformr.co.uk/rdfa/
I used http://rdfa.digitalbazaar.com/rdfa-test-harness/
With the parameters:
 - Test Suite XHTML 1.1
 - Unit Test Status="Approved"
 - RDFa extractor URL:
   "Other RDFa Extractor"  and URL http://transformr.co.uk/rdfa/
 - SPARQLer Web Service
The only difference with my JUnit tests is a Failure at case 26 and I am 
having a hard time understanding why it fails in the harness while it 
works locally on my machine.
-- 
Fabien - http://ns.inria.fr/fabien.gandon/