thanks kaynezhang.
As I could see, Alfresco native webservice is no longer developed, and all work and effort is moved to CMIS, this is the comment in alfresco WIKI: "Please note that this API has been superceded by CMIS (specifically, the CMIS SOAP binding). It's use is no longer recommended.".
I don't know if it's a good idea start a new API over something that is marked as deprecated, because maybe in new versions of Alfresco something will stop working.
That means that in future, CMIS will never offer compatibility with d:content type? What happens with people that had this type in some property in their custom content model? They would never be able to use CMIS?
Thanks!