I also found out that the DLC songs for the Vita version are just the extra songs that come with the PS3 version (because they weren't included in the Japanese version of "f" on Vita). So PS3 users aren't missing out on anything except portability. I thought they were getting new stuff ;c
*cough*hint*1stpost*hint*cough*
And yeah, the reason is cause the PS3 version is an upgrade to the previous one.
And about the sequel, Vita and PS3 version are gonna have same content, now both versions are called " F2nd "