How about .... 'heavy as a drug', or some other word instead of 'heavy'. That line is Bono being plain lazy really. And I'm pretty sure Bono has used the line 'heavy as a drug' somewhere before....
Technically though I'm unsure how it could work. There are 2 very prominant guitar parts, particularly the chords which would probably have to be played by Bono to free up Edge. However, they've worked out just as complex songs in the past - Gone, Hold Me Thrill Me to name just a couple. Personally I think its a great song, would love to hear it live.
Either they should play it in full band or not at all.. I'm sick of all those 'snippets'. I think the Vertigo Tour was about 20% of 'snippets' in the set (both U2 and other artists' snippets)!