Can anyone suggest one or two scenarios where use of Volatile documents is beneficial ? So far, I never saw anyone preferring / Using Volatile document types for business integrations.

For any synchronous call you can use volatile for example if a web service publishes and waits for response need use guaranteed

you mean volatile? well, how to handle, if the volatile doc is lost during a monetary transaction which got processed on the other system through the Web Service call and based on response, you may want to update the same in your DB / SAP system ? How is it beneficial in this case?

Webmethods supported different types of message consistency driven by the need for speed or content protection. This now manifests itself as volatile (ram only) or guaranteed (ram AND disk). The latter is the preferred option if you want recovery of process (irrespective of how that process is implemented) or if the information is business critical and must be resilient to environmental failure. It stands to reason that if the information is not business critical or meaningless on its own then there is no point in making it recoverable. Typical use cases might be information that is continually updated such as time, stock price or ping or perhaps the message exchanges within a higher level business process when recovery is through the rexecution if the process and not its subparts.

I would use it for non business critical , frequently repetitive process especially where the data size is quite large ...

Typo error web service waits for response need NOT use guaranteed

Thanks Tomasidn & ansari4u ; that gives better idea!