playing a New song is really impossible, because i doubt if they have Any new song at all, Gilmour and Waters have their own new written song, but nothing for the band.

Having 15 min to play, imagine they decide to play a long one like Shine on, or Dogs, so even 15 min isn't enough

i'd say Wish you were here, because Waters been playing it on every charity show he attended. Also for everyother song that they're gonna play, they need a full band, another keyboard player, another guitarist (sometimes 2), Backing Vocals.... so its almost impossible for the 4 of them to play such songs on Dark Side, Or The Wall all by themselves. but anything they play will make me happy, i don't really care...