I bought LRB specifically to export the songs into RB2, and ended up really enjoying the game! Now that I've played the Story mode once and did about all I want to do in LRB, I like having the songs in RB2, especially since it adds the amount of songs by other artists, and Like doing a "Queen" set or a "Spinal Tap" set.
I can also live with having my life ruined by having "Kung Fu Fighting" show up in mystery set lists in RB2. Man, I hate that song on Expert! :P