Hi maynerd,
You can read more about mattress pads in post #10 here but they are not the same thing as a mattress protector and are designed more to change the feel or performance of a mattress that needs some “fine tuning” and not so much to protect it. In the case of your mattress pad it would likely affect the feel and response of your tempurpedic mattress so it wouldn’t feel or perform the way you tested it although this could be an improvement or may make your mattress worse. Some mattress pads have a dual function and will protect the mattress from body fluids, skin cells and accidents as well as changing how it feels but yours is designed more to affect the mattress than protect it.
Post #89 here has more about the pros and cons of different types of mattress protectors that are more designed to protect the mattress than change how it feels and includes several links to several similar options that can help you make the best choice for you. A mattress protector is an important part of a sleeping system to protect the mattress and to keep the sleeping surface clean and hygienic and to prevent any stains which will void the warranty.
The Dri-tec protector and the Cool Shield protector as well as the Tempurpedic are the “thin membrane” type of protectors that are semi breathable but either waterproof or highly water resistant but because they don’t breathe as well as other types the tradeoff is that they can affect the sleeping temperature of a mattress for some people. Using natural fibers or some type of temperature regulating fabric in the protector can sometimes help offset the increase in sleeping temperature to some degree. There are also other factors that can affect the sleeping temperature of a mattress as well (see post #2 here).
These types of protectors are the most common choice with a memory foam mattress because they tend to have less effect on the feel and response of the memory foam.
Phoenix