I'm no expert by any means, but with the few bamboo backed bows I've owned/shot vs. all wood bows made by the same fellow, there wasn't a big difference in speed at all. Guess it could help some designs more than others.

Deflex/reflex is a type of design--deflex is where the riser bends away from you (adds to forgiveness/stability), reflex is where the limb bends back towards you (added speed/performance). Some bows are reflex/deflex/reflex, some are just reflex, some are straight, etc.

I perfer a mild to moderate deflex/reflex design in longbows--these have the best performance and least handshock (properly made anyway).

Chad