Any end user who wants to transfer slide between a local site (PMA.start) and a remote one (PMA.core or My Pathomation) or between two remote servers (PMA.core and My Pathomation interchangeably).
Users that are primarily focused on My Pathomation should also have a look at the recent upload capabilities added to PMA.start. PMA.transfer relies on PMA.start anyway, and for many simple straightforward scenarios, the built-in functionalities of PMA.start (or even upload functions in My Pathomation itself) may be sufficient.