Letters are now going out to Bank of America investment clients explaining that in a couple of months, their accounts will move from Fidelity’s National Financial trade clearing and processing platform to the Merrill Lynch Pierce Fenner & Smith clearing platform, according to former BofA advisors.

But what seems like a minor back-office move could make a world of difference to BofA [BAC] clients and advisors.

Bank of America Investments (BAI) advisors officially became Merrill Lynch advisors in October, according to BofA spokesman Matthew Card. He said all new accounts since then are already on Merrill’s platform.

But questions surround what will happen to BAI clients when Merrill transitions their accounts from National Financial. Merrill will likely impose its account minimums on advisors, according to advisors and a former Merrill manager who declined to comment but corroborated the details of this story.

This might work in the high-net-worth world of the traditional brokerage, but bank-brokerage clients won¹t necessarily meet Merrill¹s $250,000 minimum to work with an advisor.

BofA clients who don’t make the grade at Merrill will be shunted to a call center, according to a former BofA advisor turned independent. Card said that clients of any account size get to choose whether they want to work with an advisor or a call center, although “our Direct Investment Division will generally serve clients with a combined banking and investment relationship of less than $250,000.”

In other words, clients with less than $250,000 in assets generally prefer not to work one-on-one with an advisor.

Carl Cafaro, a legacy BAI advisor and team-leading $2 million producer in Newton, Mass., said he doesn’t think Merrill is likely to enforce its minimums.

“Everything I’ve seen in writing is that advisors can run their books as we want and that there will be no mandatory movement of clients,” he said. “As an advisor, you could look at your practice and focus on clients with more money, but nobody’s making you do it.”

The former BofA advisor, who did not wish to be identified, disagreed with Cafaro. “Before I left, they gave us our runs of all our clients earmarked for the call center,” he said. “Wave One was for clients under $75,000, Wave Two was clients under $100,000 and Wave Three, which was after I left, was for clients under $250,000.”

Advisors agree, though, that Merrill’s platform is more robust. A former BofA advisor, who moved to a competing big bank, said, “BofA ran it like a second-class operation in terms of tools and technology and compared to where I am now there’s no comparison. It’s unbelievable how behind the times BofA was.”

The big-bank advisor said that at BofA his list of available funds to recommend was 130 to 150 strong, and didn’t include the popular American Funds, which notably doesn’t pay institutions for order flow as other fund families do. By comparison, his new firm lists 3,000 or 4,000 available funds.

But at legacy BofA, clients could sit down and talk to an advisor regardless of how much in assets they had.

“You’ve got to have personal service – a lot of BofA clients are under $100,000,” according to the independent advisor. “They deserve being able to visit a broker in a branch.”

“You don’t get people used to a level of service and then take it away,” the big-bank advisor said. “I have a lot of clients who weren’t happy at all with the way they were being treated. You can’t tell me this is the right thing for customers, but do they [BofA executives] really care about their brokerage clients? I guess they just want to let that business go.”

Card, who concedes most sub-$250,000 clients will choose to work with a call center rather than in person with a Merrill advisor, said that there will soon be Merrill advisors in BofA branches. The bank rolled out an in-branch program late last year in Boston, Chicago and Seattle, in which advisors “offer clients access to face-to-face assistance (within their local branch) with organizing their finances and developing a financial plan using Merrill Lynch’s world class analytical tools and technology.”

Card said that these advisors help “ensure that [clients] are introduced to the appropriate Merrill Lynch service channels that best meet their needs.” The program, which Card said has met with success, will soon be rolled out in other areas of the country.