I have listened at least one time each cd, so I can correct the list I did! First thing that comes up to my ears is that some of the songs already released are actually different!
In particular:
CD 2
1. Sunseeker (radio version) -> it's a brand new radio edit, based on the 2001 mix of the song. The version on Decadent (and on Critical Energy) has a longer intro.
CD 4
1. Freaks (radio version) -> it is a completely different version from the previous edit. And, IMHO, doesn't flow as good, but it's probably because my ears are used to the other two versions.
2. Voyager II (urban version) -> sounds slightly remixed, plus the ending has been shortened, if I don't go wrong. Should compare it to the version on Decadent.
As for Change and Virtual Isolation, they sound pretty much the same but I'm not 100% sure