I'm not saying they don't or shouldn't ever use tapes (the backing vocal tapes on BD were especially noticeable on their SNL, Grammy and other appearances during ATYCLB), but where they feasible can, they should try to stick to live.
ABOY can feasibly be played without adding the taped rhythm tracks (i guess, this is dependent upon Bono learning the very easy chord progression and playing it while singing...he can play guitar on some songs, while he sings...though, admittedly, you're always waiting for him to strum the guitar at least a couple times while he's actually vocalizing...)
Maybe Adam can play rhythm guitar, and Bono the bass?!
Plus, how cool would it be to see Bono rocking out on guitar (as he seems to be doing, kind of, at the end of Gone on Live From Boston dvd)?