Did you find the limbs with the carbon to shoot differently? The reason I ask is I built one with carbon, don't really know if it was faster or not. Didn't live long enough to run through the chronograph, but it felt different when I shot it, totally dead in the hand. I am working on another with carbon only on the back and hopefully with better results than the first.
I tend to agree with the corewoods make only a very small difference. The design is much more important, but one or two feet here and there can make a good bow into a great bow or at least when to comes to speed.