So your saying that gross high temperature oxidation in the root pass(sugar) is acceptable?
While P11 has less chrome content, I've seen cases where, due to poor fit up, the formation of sugar was inevitable because of the time the metal was held at welding temperatures trying to fill a gap that was wider than the filler metal.
It has been my experience that the higher the chrome content, the greater the likelihood of bringing these internal root conditions into existence. Also, the choice to purge or not to purge is usually budgetary in nature.
I'd be willing to bet that under magnification, the microstructure of an un-purged, open root, chromium containing material would differ from an identical weld that was purged.
Dale Simonds