Thanks bro
Actually that would be a good idea, whatever material is on your object when you render it out is what will be rendered on the AO map. So yeah it would be smart to make the material white, or just a brighter color in order for that to work even better in photoshop. Really you can use whatever color you want, I just usually leave it on grey because I've found I use the AO maps as reference to where objects are intersecting each other, it really helps me see how they all work together.