With Guitar Hero 5, Neversoft and Activision are delivering a hotly requested feature introduced in Rock Band 2: the ability to transfer downloadable content from one game to another. Your Guitar Hero: World Tour downloadable content will work just fine in Guitar Hero 5, but there's a catch: it won't work the other way around, according to an Activision rep who spoke with Destructoid.
"The advancements and innovations made to the franchise do not allow for downloadable content to be backwards compatible with Guitar Hero World Tour," said the company.
Rock Band and Rock Band 2 do not currently have this problem. You can purchase downloadable content released that's been released after Rock Band 2 dropped and use it in Rock Band without issue. Whether Harmonix and MTV Games will able to maintain such promises as the Rock Band gameplay evolves remains to be seen, but there's evidence it's already an issue. The Beatles: Rock Band downloadable content won't work in other Rock Band releases, nor is there an export music option, ala Rock Band.