[polymatter]

Will people change banks for it (compared to say, vague promises of better customer service)?

Will people pay a premium for it (compared to say, offering more air miles)?

I'd be willing to bet that for most people it simply isn't worth the investment for them.

[brk]

Will people remember to use 1235 ONLY in an emergency? And never accidentally use it? And never use it when they feel "threatened" by the scary looking hipster hanging out by the ATM?

I would tend to guess it would cause more problems than it solves.

[atakan_gurkan]

Exactly! I would just be repeating what you say, but I'll say it anyhow. False positive rate must be considered before putting such a measure in place.