'Trace' debug pin connections are only used by, well, TRACE debugging options. So firstly you would have to have a trace-enabled tool (like J-Trace) to even expect to do anything with those pin connections. Secondly, while I have such a tool I have found it 'necessary' only once to dig to that detail level; to find an MQX bug. Most problems are not worth forcing yoursellf to deal quite that deeply into cycle watching. We have used MII here and J-Link tools (restricted to the 10-pin debug header) with no other programming/debug limitations. And of course we only use MII when we are forced into it -- RMII is more efficient.
--ERGII