Editor's note: This story has been updated to clarify some language and quotations.

The buzz over online and mobile ordering for quick-service restaurants has grown in recent months, but at least one industry analyst remains skeptical of the concept.

In August, The Melt, a gourmet grilled-cheese sandwich and soup concept, launched in San Francisco with online ordering. Some Sonic Drive-In restaurants in Arizona are testing online ordering. And service provider Snapfinger said it has developed technology to ensure the quality of pre-ordered take-out food.

In the past, quick-service restaurants avoided online or mobile ordering, as it seemed that the technology was unnecessary for the speedy establishments, unlikely to generate significant incremental sales, and could even cause food quality problems.

“It is an interesting idea,” said Brad Ludington of KeyBanc Capital Markets, which conducts paid investment banking services for Sonic Corp. “But something that is a big concern of mine [is] how do you guarantee quality? … If the food quality suffers, you run the risk of hurting the brand.”

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Larry Miller, a managing director and restaurant analyst for RBC Capital Markets, said operators for several years have introduced technology to increase efficiency in the back of the house, such as kitchen display systems and automated labor scheduling software. “Where I think it can be most impactful currently is enhancing the customer ordering and customer service experience,” he said.

But Miller noted that the challenge with all customer-facing technologies, such as tableside touch-screen terminals, is that “the order needs to be fulfilled and food delivered seamlessly to complete the customer experience.”