True. I was just saying, I wouldn't be surprised if the reason I gave is another reason why Sony decided to do it this way.
Don't say that. I love that film. Be thankful you bought the HD-DVD because the BD sounds worse. The HD-DVD has Full-rate DD+ (1.5Mbps) but the BD only has DD5.1 @ 640Kbps.
I own the HD-DVD too. Isn't it funny that only a few years ago we all thought Full-rate DTS on DVDs was amazing (which should sound the same as Full-rate DD+) but today it's considered poor. Times move on.
It should sound identical, presuming the master they used was the same. In other words the audio master tends to be the same if it's a disc with both PCM/TrueHD/DTS-HD MA, so it should sound identical.
If however, another studio used a better master for their release of the same film (maybe they've remastered it) then one could sound better than the other. That's obviously because of the Master used not the resultant Format. An example of this is the Hong Kong BD Flash Point which has PCM and DTS-HD MA, but it's thought they used different Masters as the PCM sounds much bassier (actually too bassy). You can read the review here:
Apparently in this case the DTS Legacy Core actually sounds better to the PCM.
PCM is a RAW Uncompressed Lossless Format, both DTS-HD MA and TrueHD are the same PCM audio just encoded first (which results in a lot less space being used), but when all three are uncompressed they're all bit for bit identical.
If you want an in-depth answer, read this excellent article:
Uncompressed (PCM) vs. Lossless Audio (Dolby TrueHD/DTS-HD MA)