I'm on GP4000Ss after years on GP3000s. I'm about 180lbs and I get probably 2000-ish miles from a rear, which has remained fairly constant despite the change in model. I usually have 95psi / 100psi (F/R).

I don't think that's bad, given that they are lighter tyres (less rubber to start with) and made to be grippier (softer compound, although I think the main running belt has a harder-wearing compound than the peripheral areas).