RE: 100 grain vs 125 grain?
Personally, I would stay with the 100 gr. heads and add the weight with a step or two heavier shaft.
This increases the spine strength while distributing the weight equally along the length.
There is an often overlooked benefit: the fletching, vanes or feathers, have to stabilize the arrow. More weight on the front end = less efficient stabilization. I say overlooked because you don't actually notice this when shooting while it's calm, but add a 10-15 mph breeze and see the group open up. The heavier points opening the most.
I tried this last spring and went with 85 grain points and heads and added 30 grains to the arrow weight. I'm even thinking about adding another 8-10 gr.
My 2.5 cents worth.
Shoot often - Hunt always