Kirk:. The old boys that used to say the "cores don't matter on a glass bow" are full of horse feathers...
Absolutely true. Just add a piece of purpleheart or bloodwood to a stack and see what happens to the poundage.
It is simple to figure out stacks for specific woods but play with adding carbon or very stiff wood to the core and you really have to be careful to not end up with a very heavy bow.
Something I have always wondered is this. Stiffer lams add draw weight but usually are heavier apples to apples. So since we have to grind them down in dimension , take weight off in order to hit a specified poundage. (this can be done by adjusting the stack or by side dressing the bow or sanding the glass) it is my opinion that we may as well stick with something like maple or actionboow since we end up in the long run with close to the same weight limb.
Limb recovery is the desired thing here and that is accomplished first with limb geometry and design plus the addition of proper tapers , core woods ect for that specific design.
I believe that this is achieved only by experience and a lot of experiment. I sincerely doubt that the bowyers that would say it doesn't matter have really spent that much time experimenting with different woods as cores, However I will say that of the woods we generally use as core woods there is no huge difference. Difference yes but not really huge. However is is definitely one thing in the equasion.
God bless, Steve
God bless, Steve