We have four levels of warmth (and sweatiness.) First, mesh binders have only binding layers: three in the front, and one in the back. These are light and breezy, easily our most breathable option.
Second, layered mesh binders have a single thin layer of fashion mesh over the binding layers. They breathe well and are ideal for summertime.
Third, fashion binders with a solid color or a print can get sweaty. There is still a mesh layer next to your skin that keeps the sweat from sticking close, but they need to be washed frequently.
Finally, reversible binders, with a solid color or a print on both sides of the binding mesh, will definitely get warm fast. Sweat will collect on the innermost solid layer and stick it to the skin. Not recommended for hot climates.