As I understand it, spine selection caters for archers paradox. So, if you have an arrow the bends around the handle when loosed from a 40# bow just right, and flies straight (after a little wobble of course), and you then make the bow more center-shot, would it not now bend around the handle and fly right? Me thinks.....
How much would depend on the handle change. Can most probably be compensated for quite easily.