honestly Ralphie and this is not to take away from your experience and what you are hearing, i think there might be a separate issue where a certain Stereo mix just has more balls on a certain setup than the 5.1. not always but sometimes.
meantime, it wouldn't be the first time a reviewer made a genuine mistake and/or got some bit of technical info wrong, or just preferred a certain mix or mastering or disc to another without really doing a meaningful comparison, or (shock horror!) relying on
memories.. like the 4-corners of my Quad mind!!
there is also the (to me, feels slim) possibility an advance copy for review had DTS HD-MA and the final retail version doesn't for some reason and is only Lossy. ah i dunno.. i'm Verklempt across the water!