Well, the wood grain would certainly look much better (and it is only a model ) but...
Looking at photos of the version you are building, as well as other versions of the Russian Aerosled, they all seem to show the same thing. Whether they were wood or metal, they appear to be painted in a dark color with a light colored leading edge. (Like black with a bare metal edge for instance.)
I know these aren't the same versions, but these are some of the better photos.
That looks like a one piece carved wooden prop to me ...there's no join at the base of the prop ,and metal props are seperate blades ! .... So go with wood .
most high end piston fighters during WWII had metal props probably beacuse they where more durable, but... i think a variant of the Focke Wulf had a wooden prop.