Adding weight to the head makes the arrow behave as though it has less spine, and removing weight stiffens it.

Reducing your weight to 100 might get you closser in spine, and speed up your arrow, which would be nice. It will have an impact on FOC, but what impact FOC has on anything is hard to say. Most of the special target nibb points are under 100 grain, so I have think you would be well on side with 100, though I am just going by your numbers I don't know those arrows specificaly. I think were release shooters are concerned there is a very wide range of possible spines as long as they aren't too soft.