Basically, here is the list of jetty 9 bundles in the TP:
1. org.eclipse.jetty.http_9.2.9.v20150224.jar
2. org.eclipse.jetty.continuation_9.2.9.v20150224.jar
3. org.eclipse.jetty.http_9.2.9.v20150224.jar
4. org.eclipse.jetty.io_9.2.9.v20150224.jar
5. org.eclipse.jetty.proxy_9.2.5.v20141112.jar
6. org.eclipse.jetty.rewrite_9.2.5.v20141112.jar
7. org.eclipse.jetty.security_9.2.9.v20150224.jar
8. org.eclipse.jetty.server_9.2.9.v20150224.jar
9. org.eclipse.jetty.servlets_9.2.5.v20141112.jar
10. org.eclipse.jetty.util_9.2.9.v20150224.jar
11. org.eclipse.jetty.websocket.api_9.2.5.v20141112.jar (and other websocket stuff)

The good news is that CordovaSim and BrowserSim seems to work fine against M6 TP. However, it would be really great to have a single version of bundles to avoid potential breakage.