Not necessarily
You would have 8 folios of spell lists. One for each profession (i.e. convocation), one for Neutral Spells, and one for Grey Spells.
Each Profession would have costs for Primary, Secondary, and Tertiary, as well as Neutral (think of something along the lines of the extended spell list costs from Spell Law).
Upon reaching the point of "Becoming a Grey Mage", I would say that the ritual just changes the DP costs for their spell lists. I would think of it as more of a specialized Gift that alters the skill costs from that point forward. EA #11 already contains Gifts that alter skill costs, so this would just be another one -- one with special pre-requisites (have to know xx lists from each convocation to yy level, must be one of the Shek-P'var professions, etc).