However, Graham noted that his company suffered through Salesforce.com outages that lasted from 30 minutes to two hours. And if GuildQuality had experienced the outage that occurred last month, "our sales force would have mutinied," he said.

Graham said that despite the performance problems, hosted CRM is a viable technology. "The crashes aren't the product of a fundamentally flawed business model or product design -- they're a result of too much focus on acquiring new users and not enough focus on servicing the users they have," he said.

Other customers also downplayed the outages, noting that to date they have had a negligible effect on their companies.

However, some said any deeper problems, such as the loss of key data, would prompt a closer look at alternatives.

"What would shake my faith is if something happened to the data," said Frank Tait, vice president of sales at DecisionOne Corp., a Devon, Pa.-based provider of IT services and a Salesforce.com user. "The integrity of the data is my concern."