Winter Wind is a reformulation of the Flint Hills Cone 5/6 Porcelain.  You should not notice a difference in workability or glaze fit.  The body is almost identical, but the original included a bag of talc.  We removed the talc and added a small percentage of 120mesh molochite to maintain the average shrinkage percentage in the original version.  As a bonus, that addition also increases the green strength and reduces warpage a bit as well!