: Flippant QT2.0 ALAC is 7.8 MBs and the bit rate is 802 kbps.
: Flippant QT2.5 ALAC is 4.9MBs and the bit rate is 510 kbps.
I think this simply means that the 2.5 music could be compressed better, giving a smaller ALAC file size. ALAC is lossless, but it uses compression like Zip or Stuffit files do. I used FFmpeg to create FLAC versions, with similar results (7.4 MB vs. 5.0 MB).
This result doesn't surprise me, since I hear more low-level noise in the 2.0 versions. I believe that noise is inherent in QuickTime 2.0, not an artifact of the conversion, so it's not your fault.