Yeah, there is absolutely no doubt in my mind that sound level matching is the most important factor in comparing components. I watched the Matrix Trilogy HDDVD, Underworld Evolution BD, Hellboy BD, and Apocalypto BD on my HDDVD and BD players in the last week. It seems like all of them had different sound levels because I had to turn my volumes up and down on my preamplifiers so that the sounds were not too loud or too quiet.
So the sound levels are different among all the movies and among all the sound formats (Dolby Digital, TruHD, DTS, DTS-HD, etc.). I'm sure the sound levels are also different among all the CDs, DVD-Audios, and SACDs.
Just because it's louder, doesn't make it better.