EDIT. Mirroring service is v.2 and EPi v.6 and v.7
It is not "officially" supported to run mirroring between major versions (and hence nothing that we have in our test matrix).
With that said, mirroring from 6=>7 is more likely to work (since mirroring is baed on import/export and we have tried to ensure that it should be possible to export packages from an older version and import them to a newer version).
However in your case you want to mirror from 7=>6? In theory it might work if your package contains only pages. However if any page reference a block it will likely fail since blocks is nothing a 6 site would know how to handle.
Thanks, does it work even if the page types on the different pages are different. That will say, can I say that property A should map against property B?
By default the import side will locate the property by name so the properties needs to have same name and same basetype (e.g. string).
However there is an event EPiServer.Enterprise.DataImporter.ContentImporting (in CMS6 the event is EPiServer.Enterprise.DataImporter.PageImporting) (the classes are in assembly EPiServer.Enterprise) that will be raised before the page is imported. In the event arguments there is a property called "Property" of type RawProperty, you should be able to e.g. change names for properties in an event handler.
Simple question. Since the mirroring service has it's own version numbers, is it possible to configure it to send pages from v.7 to v.6?