If there is any benefit to be gained by HiRes it is through the higher sampling rate making life easier for the analogue circuits after the DAC. 16 bits is more dynamic range than you can hear, and with modern compressed music (of which I would guess U2 is guilty) 12 bits is probably more than enough.
So all other things being equal, 24/44.1 is a waste of money.
One caveat - if they took a little more care in mastering the 24/44.1 than they did the 16/44.1 it might be worth buying, but not for the extra 8 bits, just for the better master.