I dunno if in the credits it just plays the song the game just played (mostly final boss)…
It did in UYA.
The music in all of the PS3 games was playing only in the credts, whereas, in the PS2 games, it played the music for whatever level the player was in when the credits were played, which would usually be the end boss, but could also be accessed on any level through the pause menu after beating the game at least once, and be extension with any music track.
I also liked the main piece of music that played during the credits of ACiT. Many other of the best tracks were on the space radio in ACiT, or the Groovitron in any of the games that featured the Groovitron.
There were tons of other tracks from throughout the franchise that I loved; too many to really remember…