Aerostich Darien pants Advise please

Hi

I'm going to get a pair of Aerostich Darien pants.

But I'm unsure wether to get the lightweight ones 160 denier or the 500 denier ones.

Will the 160 denier ones be too cold? or will the 500 denier ones be too hot in the summer?

I have got a pair of Belstaff trousers also so these will be a second pair..

Any help would be great.

Has anyone her got a pair? if so what do you think of them.

Thanks in advance