Senior finance executives are loudly urging the Public Company Accounting Oversight Board to abandon thoughts of requiring corporations to switch their accounting firms every few years.

As of today, more than 625 comment letters have poured in since the PCAOB issued a concept release last August making the case for mandatory auditor rotation. That is an unusually high number of letters for a proposal related to auditing. About 24% of them are signed by CFOs, and many others are from chief accounting officers, controllers, and audit-committee chairs, who are pushing back against the concept.

Despite getting flooded by these comments, last week the PCAOB reopened its comment period, which had expired in mid-December. Feedback now can be filed through April 22. The move was done in light of the board’s public meeting scheduled for next week, it said. The roundtable meeting will include a discussion about auditor independence among corporate executives, accounting-firm CEOs, and investor advocates.

The PCAOB floated the idea of auditor rotation last summer by asking for feedback on whether it would strengthen the buffer between auditors and their corporate clients and lead to better audits. At the time, PCAOB chairman James Doty noted that the PCAOB had found “hundreds of audit failures” during its inspections and suggested that management influence over auditors may have led to “eroded public confidence in audits.”

Currently, “auditors can’t be completely independent of management as long as they are paid by management,” noted Jack Ciesielski, president of investment adviser R.G. Associates, in his letter to the PCAOB.

The PCAOB document is not a proposed rule but could be the basis for one. The board asked several questions, including whether companies should have to change accounting firms every 5 or 10 years, and if so, whether only the largest of companies should do it. Apple, Google, AT&T, Caterpillar, FedEx, RadioShack, and Exxon Mobil are among the companies that responded against the concept.

The idea has been raised several times over the past three decades. The debate centers around a key question: what would make for more effective audits, a fresh pair of eyes (a new accounting firm) or deep — but perhaps compromised — knowledge about the ins and outs of a complex company? CFOs who responded to the PCAOB’s query are bothered by the cost and time expended in getting a new auditor up to speed on their business (a government report done in 2003 estimated that a switch can add 20% to audit costs for the initial year of an engagement).

At one point, the matter seemed resolved by a compromise included in the Sarbanes-Oxley Act. Rather than requiring full auditor rotation, the 2002 law requires lead audit partners to move off an account after five consecutive fiscal years. But it’s not as if it’s just one partner who’s cozy with a client’s CFO: many accountants and partners work on large-company audits. For example, approximately 180 Deloitte & Touche personnel were involved in the latest audit of Fannie Mae, according to Dennis Beresford, who chairs the company’s audit committee.

Still, some critics of the PCAOB proposal say that between the lead-auditor rotation and a new requirement that audit committees be responsible for hiring and firing accounting firms, Sarbanes-Oxley created enough of a barrier between company management and auditors.

In its concept release, the PCAOB noted that on average, the largest public companies have had the same auditor for more than two decades. But some companies do make a change. Apple, for example, formally reviews its accounting firm every five years, which has resulted in a switch. However, the company doesn’t want to be forced into taking that step. “A significant investment of time and effort from an accounting firm is required in order for the firm to fully grasp and address the complexities of our business, operations, accounting system, and overall risks associated with our expanding multinational presence,” wrote Ronald Sugar, chairman of Apple’s audit and finance committee.

Some companies say they are limited in their ability to change auditors. Most large companies prefer to work with a Big Four firm, and they are required under Sarbanes-Oxley to select another firm for nonaccounting consulting services. If forced to change auditors, a company could easily be left with a choice between only two firms, wrote Peter Keegan, CFO of Loews Corp.

Investor advocates are divided on the auditor-rotation concept, but some do want something else to change. Barbara Roper, director of investor protection for the Consumer Federation of America, wrote that auditor rotation is “an imperfect solution” for improving audit quality. Furthermore, she put forth the radical view that some investors, frustrated by auditors who seem to see their role as simply rubber-stamping management’s disclosures, are even questioning whether audits themselves should continue to be mandatory, given “the high price that shareholders pay for it.”

Most letters emphasized that the PCAOB has not shown a clear link between auditor rotation and improved audit quality. According to recent research by Audit Analytics, only 4 of 53 restatements made by Russell 1000 companies in the past five years occurred shortly after a company had switched auditors.