It may seem simple: Should you rinse upholstery? And if so, what solution should you use?
Keep in mind, though, the idea behind using limited moisture in an upholstery shampoo method is to inhibit cellulosic browning.
Three things can cause cellulosic browning:
High alkaline pH - note that natural fibers are very pH sensitive so be careful with alkaline solutions.
If the soil load is light, then a dry extraction is fine, as that will limit the water and cleaning solution left on the fiber, and a final step of dry toweling will be sufficient.
If the soil load was heavy, then rinsing and extracting with a Sapphire Scientific Upholstery Pro and Prochem All Fiber Rinse is a solid choice. However, that's counter to the reason for using shampoo in the first place, which is to add just enough water and cleaning solution to the fiber to release the soil's bond with the fiber without saturating the fiber with water.
If you need to rinse and extract due to the heavy soil load, you should first share with the client the strong possibility of browning and ask them if "THEY" (not you) are willing to assume the inherent risks involved in using that much water on their water-sensitive fabric. After all, it is their upholstery and their soil, so If the fabric has become so heavily soiled that a rinse and extraction is necessary, the risk, just like the soil and fabric, should be theirs.
Most important, be sure you use a rinse that leaves the fiber on the acid side of the pH scale.