The lack of elasticity is why the "high performance" materials have less shock. They put more of the bow's energy into the arrow, less resonates down the limb and that is where hand shock comes from, along with a little more speed. You may need to go up in arrow spine with the FF string due to this. Try stretching a piece of twine taut and a rubber band. Pluck them both, see which has more vibration. Kinda over-simplified, but you will see what I mean. You can also generally go a bit lower in brace height with the low stretch strings and gain a little there also.

Chad