Downloadable content for Guitar Hero 5 will not be compatible with Guitar Hero: World Tour, according to an Activision spokesperson.
The reason given to Destructoid is that the "advancements and innovations" in GH5 are too much for poor old GHWT to cope with.
Of course, the songs on the Guitar Hero: World Tour and Guitar Hero: Greatest Hits discs, and the majority of downloadable songs for both, can be used in GH5, and will make use of said updates, as long as you pay a small tax.
Oh, and Guitar Hero 5 downloadable content "will be compatible with future Guitar Hero and Band Hero games", apparently, although whether that too will cost money is not explained.
Read our preview of Guitar Hero 5 to see what those "advancements and innovations" actually amount to, and look out for our review soon.
The game's due out on 11th September on PS2, PS3, Wii and Xbox 360.