I wouldn't call this a "big theory". There's just very little test data out there today that would prove it right or wrong. So, without a lot of data to support or refute at this point, I wouldn't dare jump to any conclusions and declare the theory "shaky" or of a "thin foundation". Go ahead, prove me wrong, if you can, but present the results in an objective manner in such a way that they are based on TASTE, not facts, figures, IBUs, etc. I am confident I'll get there, eventually. I'm just not there quite yet.
In my experience, you do NOT get more of everything (sugars vs. non-sugars) as efficiency increases. This has already been proven by thousands of brewers whenever they do a partigyle session. Invariably, a whole buttload of sugar and flavor comes out in the "bigger" beer, which might often be described as "more malty", while the "small" beer made from the second runnings or even a blend of first and second will always end up tasting more lifeless and downright watery unless it is jacked up with extra steeped malt or extract. Try a partigyle sometime without any enrichment of the small beer and you'll find out exactly what I mean. I think even if you boiled the snot out of the small beer to hit the same original gravity as the bigger beer, the maltiness would seem weak and lifeless in comparison. Again, this is another experiment I haven't actually tried yet, but I am very confident that it would be true because the small beer is often so very wimpy in taste.
There's ALWAYS more to learn. After 12+ years homebrewing, I'm definitely still learning, all the time. And in that time, I've also seen many of the old brewers' tales and rules of thumb from the big wigs including Papazian, Noonan, and even our oh-so-revered Palmer and Zainasheff shot full of holes, and the ones who aren't dead will freely admit that the "rules" have changed. And by whom were they proven wrong? I was going to say "people like you and me" but it appears I might be more accurate in saying "people like me". I am not a book burner. In fact I read a TON, probably a lot more than 95% of homebrewers. But at the same time, I am a skeptic, and a realist, and I am a man of science (actually an engineer by degree). So when I obtain objective data that the sages would not be able to explain, then I am not afraid to conclude that the sages might have more to learn. And who better to teach them, and everyone else, than a simple guy like me. But like I said, many people don't want to hear it. All hail, Zainasheff [or insert alternate icon here]. To each his own I guess.
Denny, that's an interesting data point, assuming it's true (coming from you, I don't doubt it quite as much). But I might also argue that the reason Americans love hops so much is that they cover up shortcomings in the malt profile, especially when compared to the Germans and other continentals who've really got the good ingredients and processes down pat to do it right every time. Meanwhile it's not too hard to make a hop tea, put a little malt sugar in there for complexity and fermentables, and call it delicious. And when you think of Sierra Nevada, what's the first thing that comes to mind? Probably a hoppy beer ala SNPA or Celebration or whatever hoppy flavor of the day. So if their malt character might be lacking in some respect at 100% efficiency compared to what they might get if they purposely lowered it to 75%, who's going to care!? Well, I'm a malthead (as opposed to a hophead). I care about malt character. Many many many people really seem to not care enough about the malt. If they've got fermentable sugar and 100 IBUs, they're happy as clams. Not me. Which is no doubt why I keep on rambling about the need to experiment with malt flavor vs. efficiency.
Gosh, I've got to get myself a damned blog. But no one would read it. If you've made it this far, thanks for listening. If not, probably so much the better. I apologize either way. You know what I'm really doing, don't you? I'm procrastinating. Yeah, I'm at work right now. I'd better get back to it. Yeah. Bye now. Ba-bye.