Because there's no true core inside the Jazz, the effect should be somewhat to very much like that of a traditional pancake core: the more positive, the more length and backend, the less positive, the earlier and less backend snap.
How much you will see depends more on your eye and the amount of weight moved and your release. The more revs and the slower your ball speed, the more you SHOULD see. The less revs or the higher your ball speed, the less difference you SHOULD see. The sharper your eye, etc. etc.
I forgot to add this:
Negative weights (side, finger, top) in/on pancake cored balls will cause the track to rise closer to the finger and thumb holes. Positive weights will cause the track to lower slightly. Only danger is for people who track high to begin with and need/want negative weights.
"None are so blind as those who will not see."
Edited on 5/29/2009 7:08 PM