As mentioned above, the 160 stat is definitely something we recommend, even for cars with just a basic tune can benefit from the 160. We developed a 160 as a 170 was only about 6-8* cooler than stock, and while it was better than leaving it stock, we knew we needed to get it cooler than that for the best balance of power and durability.
As for the cold weather comments, Michigan gets well into the negative temps in the winter, and not once have any of our cars had problems with heat, or how they run with this setup, nor have any of our customers. The EcoBoost cars computer deems it full temp well before 160 even when completely stock.
Another benefit, beyond engine performance, is fan life expectancy. With a 170 stat, the fan will cycle off on on more frequently due to the thermostat being so close to OEM temperatures, so when we command the fans to try to regulate the temp to where it should be, it is very close to the thermostat temp. By using a 160, it allows for the engine to naturally stay in that range without forcing the fans on so often.