Make the move to Rock Band 4?

Hey all! Just wanted to get some feedback here. I currently have a few of rock band/gh games with all the instruments on ps3 that i use from time to time for family friend get togethers…. Im just curious if its worth it to move to ps4, and buy rb4 for all the dlc and such. Would I be losing out on a bunch of songs on the old games? Or would it be too expensive to match the song collection we currently have across 5-6 games on the ps3… appreciate all feedback!