I think mash-out is a control mechanism big brewers use to create uniform worts, all things considered. It would not improve efficiency - you're actually destroying enyzmes that might convert a few more molecules of starch to sugar and if that were the case, the big guys wouldn't do it. As to loosening up the mash thickness, our sugar solutions aren't saturated enough that 10 degrees Fahrenheit is going to make much of a difference in viscosity. I've even read (not that I intend to try it) that heating the sparge water isn't necessary. A lot of things that matter if you're trying to make the next million gallons of Coors taste like the last million just don't matter at our scale and I think mash-out is one of those things.