I have to disagree with your statement that "only a few" mono copies of the Sgt. Pepper album were released in the U.S. In June of 1967, most record players (for that's what they were called back then!) were still mono, and stereo turntables/receivers were still the province of a select few audiophiles. It's true that the paradigm shifted as 1967 wore on and the Summer of Love began making albums more important than singles for many artists. And it is true that mono copies of The Beatles' next album, Magical Mystery Tour, are much more scarce than stereo ones. But I'll say this: it was certainly the mono Sgt. Pepper that I knew best, and I remember being somewhat flabbergasted by the many differences in the stereo mix when I heard it for the first time, which was at least a couple of years later.