Yeah, wood will break but only after doing a goodly woodly amount of damage to whatever it hits. I've got the scars to prove it. Beginners should just learn to keep their fingers out of the prop disc and use smaller engines to minimize the damage.
From an AERODYNAMICS standpoint (it's the aerodynamics forum after all
) wood is often stiffer and lighter but the airfoils typically used are far from efficient. But if you look at the higher end speed model wood props you'll see just what is actually possible. But your generic Zingers and similar are easily outperformed by APC plastic props just due to the poor and draggy airfoils.
But oddly enough the difference isn't as much as one may think. A buddy and I static thrust tested a bucket full of props in our early electric days. The coarse club like shapes of the Zingers were about 15%'ish less efficient than the equivalent APC. So they drew about the same current for 15% less thrust or needed 15% more current for the same thrust.
When thinned down to APC'ish thickness and shapes the wood performed within a couple of % of the performance of the APC's.