It really comes down to whether you want to adjust the valve every once in a while depending on the cold water temp. Is it worth $172 to not have to adjust. Both valves do their job very well.

Im not familiar with either but being intrigued with your question I did a little quick google research(gotta love google). Without reading everything there it would appear that Delta's "scald-guard" was their original technology and the tempassure is newer. Google is full of closeouts and surplus ads for the Scald Guard which may account for the price difference.

gslgal,

Building codes now require AntiScald valves on showers. There are two kinds of valves that control Scalding, one is Pressure Balance, the other is Thermostatic.

The difference between the two Delta valves is this;

The Scaldguard "Monitor" valve is a pressure balanced valve. If cold water use occurs somewhere else in the house suchas clothes washing, toilet flushing, irrigation system turns on, the pressure in the cold water system drops. This pressure difference will effect the temperature in your shower by reducing the cold water flow through the valve thus increasing the water temperature due to higher pressure on the hot water side. Pressure balanced valves address this instantly by cutting back on the hot water and maintaining equal (Set) pressure. Most people prefer this type of valve.

The "Tempassure" valve is a Thermostatic valve. Thermostatic valves only control antiscalding by a means of a slower acting valve which has to see hotter temps first before acting. Delta is remarketing a product giving it a slick new name.

My builder used Delta faucets including the Monitor valve in my new home. As the house was already built, I had no say in what faucets would be installed. The Monitor valve may be inexpensive, and may hold the temp once set, but is touchy when adjusting the temp. A smidge this way too hot, a smidge that way too cold. Delta valves are prone to drips after only 1 year, I guess thats way it's so easy to find replacement parts. I will be replacing faucets with Kohler products with ceramic cartidges which now have a lifetime warrenty.

Hope that helps,

Dan Martyn

Here is a link that might be useful: Delta Faucet