There are many other items to consider in choosing windows. Daylighting is important too. In your haste to reduce solar heat gain, don't pick a product that cuts too much visible light. If the occupants of the building have to turn on the lights to see during the day, some energy savings will be lost. Plus, people love natural light and will not feel comfortable if it's too dark.
Appearance is often critical.
Mirror finishes and obvious colors may not be acceptable in residential buildings. The new selective glazing systems reduce the need for highly reflective coatings and strong tints. Windows are not the first line of defense for heat rejection. Exterior shading from trees, shrubs, trellises, overhangs and awnings can be more effective. By using appropriate shading strategies, you can use a glazing system with a higher SC that allows more visible light.