Well, we are getting into sticky territory here w/ across installs. Technically, a user should not be spliting this type of data across multiple portals. The thing is, depending on the membership provider (very important note after next release) each user could have a new userid. This is somewhat a lack of the module, but I think stats should count against a single forum but I just haven't gotten to it yet. Yes, there are plans to handle this later but not just yet.