TPO Versico Membrane installed in DC.Will retain dirt more easily over PVC. This is actually pollen in Spring.
Cheaper over PVC membrane. Comest on wider sheets. Less seams. Much more dificult ot do puncture repair on couple year old membrane is one drawback. Copper counter flashing and A/C unit elevanted. Future step can be to upgrade the plastic bubble skylights with Velux inulated glass.