I'd say Llama fits for one of the hardest Full Band, Pro keys is hard, Pro guitar is hard, Pro bass is bat**** hard, Drums are awkward hard fast beats, basic guitar/bass/keys are a pain. But I don't think it should sit alone there. Paradise by The Dashboard light might not be devil-tiered on everything, but the vocals aren't that easy, either pro keys nor drums. Andromeda songs should fit there too, along with Amberian Dawn, and so much other stuff. I don't think we should divide by the game's tier, but by the obvious tier.
Paradise is tough but passable on just about everything. Panic Attack is harder on most instruments, and is probably, along with Visions, the toughest 2 drum songs on a disc.