ANYHOO, getting back to brass tacks, the radiator is the first line of defense, then the fans (passive then active), as it should be. By opening the TStat earlier, you let the passive cooling take over earlier, which would be more important the "hotter" the tune. On the Edge, there is a thermal bypass valve that controls when trans fluid flows into the cooler, and it opens around 176F (normal operating temp for the 6F50). The Edge's OEM thermostat doesn't start opening till 187F and is fully open at 205F. Thus only engine cooling would be achieved below the 176F mark with a 160F or 170F TStat.
Is it the same setup for the SHO/Flex/XS? Then it would make sense for the fans to come on around 180F, regardless of the cooler TStat temp (160/170).