With the introduction of 1.6.9, I believe that advice to now be outdated. I have been using 1.6.9 since it's release, and I personally skipped 1.6.6 through to 1.6.8 due to glitches in serial processing, issues with the library heirarchy order, etc.
However, as I don't 100% know for certain the reason for Erik giving this recommendation, I haven't removed that warning myself. However, since that was the state of things in March, there is a fair chance that it no longer applies.