Seems like, in a good faith gesture, Harmonix could at least offer me the DLC I bought on Xbox360 at a discounted price for PS4. They could charge me whatever they have to pay for the songs and forgo their portion of the proceeds. Everybody wins in that scenario: the artist/publisher get their money, I get the song at at least a discounted price, and Harmonix while not making any money off the resale of the song, gets a myriad of people like me who will otherwise not buy the game, to consider hopping onboard.
Logistically it should be simple. They have hooks in Live and PSN. Let me log into each on their site, do a quick carry over of what I've bought from one to the other, and show/provide those tracks at a discount on their in game store.
I can't imagine there would be any practical issues there, and as for resources to implement it, it doesn't seem to be a terrible burden. The influx of console-switchers who would otherwise eschew the game being motivated to buy it would certainly offset their costs, considering immediate money earned for the game and rebuying of plastic instruments, not to mention future DLC sales they wouldn't otherwise get from this population of gamers. I hope they consider something like this.