You may want to look at the carbon fiber laminate over birch wood core material from Dragon Plate. Their analysis is that you only need the CF at the outer surface - not solid CF- to get the suitable stiffness characteristics. May also help further with your energy transfer issues too.
LINK => http://dragonplate.com/ecart/categories.asp?cID=3
For our kicker element, we are using an ~12" equilateral triangle, in a vertical plane, made from 20mm square tee slot channel. A widened toe at lower front corner contacts the ball and is beveled for some loft. This triangle pivots from its top corner, and has a vertical 1500lb line (1/8" x 1/4" - synthetic, low stretch) attached to its rear corner. It also has a forward travel limiting tether attached the low front corner.
The synthetic line is bungee pre-tensioned to ~50 Lbs of pull, and a CIM driven winder can draw line further back to reach 100+lbs tension. Triangle kicker element is accelerated very rapidly with minimal arc of travel to give full-field kicks. Triangle kicker element reaches high velocity and has ZERO FLEX on contact with ball (triangle is the ONLY structural shape) , thus acheiving maximum compression of ball’s surface during ~1/100th second of contact with ball. This high sustained velocity during short (1/100th second) period of contact with ball is more important than follow through, and is is the single most critical factor for long distance shots that we have yet determined.
-Dick Ledford, Robotic Colonels Mentor