The QA plugin has been tested with DITA OT versions 1.5.3 and 1.5.4. The only requirement is that your input map has @chunk set to-content. For example:
<bookmap id="mybook" chunk="to-content">
This ensures that a single HTML report is produced with errors properly calculated. We have tested with documents containing a few hundred topics; if you are processing thousands of topics, the HTML file may grow rather large.