This has been a fun read for me. Lot's of topics and theories. I just wanted to add a thought on high efficiency:
One looks to achieve full conversion in the mash and then lauter the beer. Your efficiency depends on how good your mash and lautering processes are. I believe that if you hit and maintain the proper temps in your mashing and at mashout, then you should not necessarily get a grainy and/or thin beer. And if you have a good sparging process, you can have a great beer with a high efficiency because you rinsed the grains in the optimal manner-ie Sierra Nevada. Where you run in to problems with a high efficiency beer IMHO is not performing a proper mash for it (Hochkurz, Decoction, etc.) to get the correct body and mouthfeel, oversparging and/or not hitting proper mashout temps.