dont spare polys on buildings.... at least make them 600 polys... it wont lag trust me.... exep u have extremly slow PC
and yes those models sure need more details.. especialy cuz of cellshading... spare polys on units... u wont have 1000 buildings in game but u will have units.. so...hehe
anyway on buildings spare polys only on those u know it will be built in more than 5 places