Interesting. I have been a long time fly fishermen and have a substantial collection of high end fly rods. Fly rods evolved from bamboo to fiberglass to carbon, boron, and graphite composites. The difference between a solid fiberglass rod and one of the high end graphites (like the Loomis GLX) is significant - in terms of weight and line speed.

If the same technological advantage applied to compound bows, the solid glass limbs would have an IBO of, say, 275 - and the graphite composites might be 350. The difference in bows, however,doesn't appear to be all that great. Maybe the cams impart a substantial influence, compared to the limbs,in the bow's ability to propel an arrow.