Wong Seung created the 9 Yum Jen Ging. In the JY universe, the only other person who could be said to have mastered the complete 9 Yum Jen Ging was Gwok Jing. If Wong Seung fought Gwok Jing (at his peak), who would have prevailed?
I am of the opinion that latter day practitioners of a skill generally cannot master that skill at a higher level than the skill's *originator*, but this is merely an opinion, not an absolute truth. Moreover, although Wong Seung was the 9 Yum Jen Ging's creator, the 9 Yum Jen Ging represented the total body of his martial arts skill . . . he had nothing else. Gwok Jing, on the other hand, had such additional skills as Hong Lung 18 Palms, Vacant Fist, Left/Right Hand Technique, Cheun Jen Sect martial arts, and Peach Blossom Island martial arts.