I think rpc/encoded is the only supported format (at least I noticed "rpc" seems to be hardcoded). Which format do you prefer (rpc/literal, document/literal, document/literal wrapped)?
Tommy, it is not a matter of preference, but requirements. “doc/literal” is the normal way of writing web service, since you don’t have to send “type” information on the payload, so the payloads are much smaller. The encoding rules on “rpc” are a bit different of regular XML.
Anyway, another case of these needs are when you have already a deployed service, and you like to "re-write" it using Yii… for example.