Personal experience.
I withdrew a fair amount of money by asking to have the ATM daily limit increased for single days over the space of a couple weeks, and withdrew dollars in Uruguay. I promptly received a letter from Chuck to say "we're closing your account" due to "a business decision".
I called them and spoke to them and they wouldn't confirm the reason, but when I asked is it because I withdrew a bunch of cash in a fiscal paradise, the woman said "mmhmm, but I can't confirm that".
I would assume once you cross the threshold for IRS reporting, possibly with the implication of structuring, they will look at your account closely. If you have huge brokerage balances with them or something, maybe they don't mind too much, but if you're leaching the ATM fee waivers, then be careful.