really, i'd focus on the easy for mom issues.
like everyone said, i cannot imagine the horror of having to prepare and feed a bottle in the middle of the night. (or, i can imagine it and that's why i find it horrifying...)
like one great post said, i sleep so well after bfing, fall asleep so easily. i doubt i would fall asleep easily after listening to hungry crying, dealing with bottle, etc.
also, it took my breasts a long time to regulate to the point where i wasn't in pretty serious pain and really really WANTING to feed the baby before he even woke up. he would sleep a little longer, my breasts would learn to go a little longer. maybe this would be resolved in a few days with the cold turkey at night method, but i doubt it since it took a good long time to adjust to the eventual sleep through the night.
and, yeah, the studies and annecdotes about ffing not necessarily causing longer sleep periods.
but, hey, this poor woman may have a lot going through her head. maybe she's planning to/needing to go back to work very soon after birth. maybe she's had problems brought on by sleep deprivation before (more than just "it makes me grouchy"). sleep deprivation can be a serious issue and just dealing with it because it's best for baby may not end up being all that great for baby (if mom ends up severly depressed, for instance, which can be brought on/aggravated by sleep deprivation).
i guess i'd recommed gently bringing up the main points that run through these posts and getting her in the mind set of try it out and see how it goes.
it took me about 3 months to be really happy with bfing and now i'm SO glad i did it (not that i really seriously considered stopping...) and part of that is that i know it's best for baby, but a lot of it is the convenience for me. no waste, little mess, totally portable, totally perfect. i've done so many fun outings and trips that would have been a nightmare if i was carrying formula!
and now that ds pretty much always sleeps nice and long at night, i don't even dread the few nights he doesn't because it is SO easy to feed him back to sleep (and i don't even co-sleep, it's still easy).
ooh, and totally about the nasty formula poo. we use cloth diapers, so that's a major plus for me. i'm delaying solids as long as i can!!!