Just found this thread while doing some googling. Hopefully all the debate over the mono mixes being the ones that George Martin and the fab four created vs. the stereo being secondary have been laid to rest, now that the remasters came out in 2009 and that was confirmed as fact in the surrounding commentary.
I have the mono and stereo remaster sets. I believe they did a better job of doing the stereo remasters than the mono. The stereo sounds brilliant - sparkly, clean, deep, detailed, punchy. Spectacular job of remastering. These sound really good. The mono box set is more of a historical archive, a filling of a gap that had been missing for all these years on cd. Now the mono mixes are available on cd, but they didn't do too much towards making them sound "great".
Having listened to both, I prefer bits of one and the other. I love the mono mixes, but like I said I think the stereo remasters have better sound quality and are more enjoyable. I agree, though, I don't like the hard-panning left and right of the mix.
However..... I have recently gotten back into vinyl. Through the wonder that is eBay, I laid hands on an original 1967 UK first pressing of Sgt. Pepper in mono. Wow. Let me say it again. Wow. The mono vinyl blows away the mono cd from the 2009 remasters. I don't have an exotic turntable, either, just a simple Thorens TD166 MKII with a Shure MX97E cartridge (cartridge is sold on Amazon for $79). And I have a $1000 cd/sacd player, which sounds unbelievable. The mono remaster to me sounds sterile and laid back, whereas the vinyl has so much power, kick, detail, and clarity. It's everything you want Sgt. Pepper to be. John Lennon once said that you haven't heard Sgt. Pepper until you've heard it in mono. But he died before the cd age. I think if John were alive today, he'd be saying that you haven't heard Sgt. Pepper until you've heard it in mono on the original vinyl!