If you were to make all hidden tracks their own separate tracks, and take a look at each of the penultimate songs of Coldplay's career, you'd find Everything's Not Lost, AROBTTH, Twisted Logic, DAAHF, DLIBYH, and Fly On. That's a pretty amazing set of songs in my opinion (except for DLIBYH...) so I hope Colour Spectrum will be solid. It has a lot to live up to.
Edit: I guess there's the possibility that X Marks The Spot is after Colour Spectrum or Up&Up so this entire post might end up being irrelevant. :lol: