Just go with the looks. The casted one is prob only 500g-1kg heavier.I haven't found the 57F pro in 17", but as i prefer the 57pro, i am not too dissapointed - the price of the 57pro is a little hard to digest for a 2 piece cast rim, as the forged rims are about the same cost.
so the question is, are forged rims genuinely better/superior to cast?
and what offsets would you recommend for standard suspension?