A survey of 350 CFOs conducted last summer by software-as-a-service (SaaS) cash-flow operations firm Bill.com found that when CFOs automate their accounts-payable process in the cloud, the AP department cuts its work time by more than half, and slashes the cost per invoice by up to 70%.

But 73% of the respondents said they still use Excel spreadsheets to record and process invoices.

So what’s stopping CFOs from getting their head into the cloud? When asked to name their biggest challenges in moving to a cloud environment, 64% of survey respondents said integration with existing legacy systems, 55% cited system and network security, and 44% noted the trouble and work of introducing new processes.

Moving AP to the cloud “reduces manual intervention in getting the invoice from A to B and back to A,” says Chris Pang, principal research analyst at Gartner. But the familiarity finance departments have with whatever system they’re already using, and the minimal costs associated with continuing to use it, have been leading many finance departments to close their eyes to the benefits they know they can get from the cloud.

Indeed, most CFOs can tick off those benefits: not running and maintaining your own servers; the ability to adopt new technologies through a simple download; the opportunity to leverage mobile devices because, in the cloud, your data is accessible anytime from anywhere; the freedom from large capital expenditures on perpetual software licenses.

But not changing is always easier than changing. “Remember, most PCs come preloaded with Excel,” Pang points out.

There comes a moment, however, in any growing business’s life when the processes that got it started begin hampering, not enabling, growth. Brian Preti, vice president of finance at e-commerce platform provider Demandware, says the company only began using cloud-based financial-management software in 2008 after QuickBooks’s limitations gave him little choice.

When Preti started at Demandware in 2007, it had two subsidiaries in the United States and one in Germany. Reconciling reports from the three units in QuickBooks, he says, created “headaches.” QuickBooks couldn’t consolidate Demandware’s German subsidiaries’ euros with the rest of the company’s dollars. And it couldn’t create invoices in multiple currencies, either. “We would have to create different invoices with Excel in different denominations and do the [foreign-exchange] translation manually. Then we’d input that into QuickBooks,” says Preti. “My world was Excel spreadsheets, and it quickly got out of control.”

So Preti shopped around, looking at cloud business-management giant NetSuite and Microsoft Dynamics financial-management software before settling on Intacct, an SaaS financial-management and accounting company.

There are many cloud-based financial tools, among them Host Analytics, Xero , and even QuickBooks online. Preti went with Intacct primarily, he says, because he thought it “would be able to handle our anticipated growth.”

Gartner’s Pang points out that Preti probably could have found a solution in on-premise software, too. But then he would have lost the real-time visibility for all stakeholders that cloud software can provide. And lack of visibility can increase the risk of reporting errors.

Demandware gave itself one fiscal quarter to implement and become familiar with the Intacct software and processes. “We nailed it,” Preti boasts. “My team and I participated a lot in the implementation. It wasn’t just having a couple Intacct folks come up here and get it running in two or three days. It was downloading information out of QuickBooks and putting it in templates and sending it along to Intacct.” Intacct put the templates in its cloud, then Preti checked the data once it was made available to him. The cost to get the system installed, up, and running, Preti says, was low compared with the cost of a perpetual software license.

The savings from cloud financials, says Pang, come less from the software itself than from reduced implementation costs. The fact that cloud implementations are largely done remotely, and the configuration work is done by the provider, saves time. Consequently, the finance department’s productivity during implementation takes less of a hit.

Today, there are six Demandware subsidiaries and, according to Preti, the finance department operates more efficiently than it did when there were only three.

So are there legitimate reasons not to adopt cloud financials?

“A lot of companies are going to the cloud thinking it’s going to be cheaper, faster, and more secure. And that could be true,” says Larry Litowitz, who has been CFO of several cloud-service providers and is now a partner at management advisory SCA Group.

“But some, by year two or year three, find out they’ve made a mistake. Yes, they don’t have their own server sitting there hosting their data and costing money, and maybe they’ve gotten rid of half an IT person, but they still have the whole accounting staff and most of their IT people, and now they’re communicating with outside parties.” All these complexities add costs, Litowitz says. “The ROI [for cloud] is not always what CFOs think.”

But Preti says that once growth companies reach a certain size, they’ll find the decision to move to a cloud-based financial system becomes less of an “if” and more of a “when.”

“At some point,” he says, “small businesses will start seeing pain points emerging between recognized and deferred revenue, and foreign exchanges and consolidated reporting. Once a company today reaches any of those points, they should know there are better solutions than QuickBooks out there.”