Right, I have the Perfect Album btw The original release from back when (available on this site) has the uncompressed level musics in their basic form, this one has all the mixes, but they're pretty much the 'game versions' if you will. It still doesn't really reflect the PS2 release though, and although the Sonic into dreams music is on the disc that doesn't mean anything about the content of the PS2 version of the game.
That´s why I separate dreams dreams sweet mix in holy night. But about the content in the game, you can´t hear every track on the sound test (for example you can only listen to the normal version of the stages songs, and the nightopian version of dreams dreams), so it´s possible that there are more things on the disc. Also there are two more secrets coming soon in the official website, but they are probably about new year.
Now i think that they should have remade know thyself!, because they put it in the disc like when they put it 12 years ago. And from all i hear, the tracks are slighty improved.