I've heard this assertion before, but I don't see how a lower thermostat will make any difference in most locales except in the winter time. Assuming the t-stat is wide open (as it normally is in the hot summer months), it doesn't matter if it opens earlier at a lower temperature or not...the engine is going to run at the temperature the cooling system can achieve whenever the t-stat stays wide open, regardless. If it's running over 180, a 180 t-stat or a 160 t-stat or no t-stat are all the same. The thermostat is to regulate the cooling system's water temperature to ensure that it isn't too cold, not that it's not too hot.

With the supercooler, the engine will run hotter because you've robbed some of the cooling capacity of the cooling system by placing the supercooler in front of the condensor and radiator. You would do better to go to a bigger or more powerful fan IMO (or you could just turn off the AC for that matter, but who's gonna opt for that...).

The reason you can potentially get away without a reservoir on the charge air cooling system is that once you add the supercooler and separate it from the engine cooling system, it may never get hot enough to require much expansion surge; the rubber hoses take up the minimal expansion without overpressurizing the system. Probably fine for a daily driver, but I question whether you might still need some extra surge if you're racing the car or running it really hard in hot weather. With this in mind (and being in southwest FL) I opted for BrianBrave's extra tank.