MnFn,
If I may jump in here regarding your question for Pavan: I shoot both Doug Fir and Sitka Spruce. Much prefer Doug Fir, but can't always find it in the weight range I need for my 45# bow.
I shoot the same spine with both, but do notice they fly differently.
They end up in the same place, but the Fir's seem to have a straighter
line to the target, the spruce wiggles a little more but may have a marginally flatter trajectory. I figure it's the fact that the spruce is lighter.
From ny stumping practice, I'll say that I trust Fir to be stronger, for sure. Neil at Hildebrand said the same once when I talked to him about the two shafts.