Image: Group of business executives standing in a row at a bank counter © Purestock, Getty Images

When Melissa Sullivan recently decided to switch her checking account from a large national bank to a smaller, regional one, she expected to enjoy a new level of customer service and reap the benefit of lower account minimums.

What the Florida marketing administrator didn't expect was a series of hassles, from surprise debit fees (when her initial deposit took far longer to clear than anticipated) to a glitchy online bill-paying system. In the end, says Sullivan, the negatives of the switch have far outweighed the positives. She now wonders, "Why does anyone do this?"

It's a question more banking customers may be asking these days, as record numbers of people move money from one institution to another. Nearly 10% of customers made a change with their primary account in the past year, according to a study by J.D. Power and Associates -- a share that has risen by almost 25% just since 2010. So far, analysts say, most of the shifts have been in favor of smaller banks and credit unions. In fact, membership at credit unions hit 92 million last year, a record high.

The key driver behind all the switching, say industry watchers, is consumer dissatisfaction with the high fees that have become increasingly common in recent years. Add to that what Steve Beck, the founder of consumer-research firm cg42, calls "a broad range of general frustrations," from long wait times at branches to rigid processes for a variety of transactions, and you end up with customers looking for an alternative. Banks themselves are also hastening the trend, as they roll out generous account-opening promotions with high starter interest rates and cash rewards to capture the disaffected.

Still, for consumers, there is one mighty big catch, experts say. Even if New Extra-Friendly Savings & Loan looks better on paper than Old Fee-Sucking Bank, the switch is never simple in an age in which consumers consolidate so much of their financial lives -- from investment accounts to home-equity lines -- in a single institution. Further complicating matters: In today's autopilot-driven financial world, customers typically set up their accounts to issue regular payments and accept direct deposits -- transactions that can all too easily fall through the cracks during a move, leading to penalties, late fees and horrors like missed mortgage payments.

Financial pros, though, say savers eager to switch can protect themselves in several ways. Keeping both old and new accounts fully active for at least three months, for starters, should guarantee that all automated bill payments and direct deposit arrangements transfer from one account to another. Garth Scrivner, a counselor at StanCorp Investment Advisers in Albuquerque, N.M., urges even more caution, telling clients to wait up to six months before closing the old account. That, he says, will also "allow them to be sure the grass is really greener on the other side."

Other possible problems with switching can be resolved in a similar fashion. For example, given that your initial deposit check may take time to clear, experts recommend making that first deposit in cash or with a cashier's check, which speeds the process. Pros also say it's worth asking a potential new bank if it offers a "switch kit." Such packets include checklists of the financial data you'll need to gather and, often, form letters to authorize any necessary third-party transfers.

Of course, before you take the leap to another bank, advocates suggest one more often-overlooked task: Check with your current bank to see if it can offer better rate terms or waive those cringe-inducing penalties. As experts point out, given the huge number of customers willing to jump ship these days, they now wield more power than they might realize. Says Beck, "The takeaway is not to look at this as a one-sided negotiation."

More from MarketWatch.com:

Click here to become a fan of MSN Money on Facebook