I think I know why I want WoD MultiSphere to work; it just dawned on me why (perchance) it irks me so to find that the way 'game mechanic X' doesn't work the same way in System A, System B, and System C:Dark Ages.
Long ago and far away, Chaosium decided to lump most of their RPG systems together. Call of Cthulhu (based on Lovecraft stories), Pendragon (Arthurian RPG), Stormbringer (the world of Elric, a Moorcock character), Hawkmoon (or is it Hawkwind? Another Moorcock character), and perhaps a few others were deemed to be in the 'Eternal Hero' series. The notion was that there was a multiverse out there, and in each you have the forces working to bring the world to an end and the forces working to stave off that end. Each of these systems were showing a different world of that multiverse, although some had problems.. in Stormbringer, the main characters are often working to bring about the end instead of working against it (Anti-Heros). In Call of Cthulhu, there are no superhuman forces working for 'good' and it's just humanity versus a universe of crazy-evil.
The end result of this were a slew of systems that one could, in theory, transfer a character out of one and into another. Much like what TSR tried to do to blend D&D, Gamma World, and Boot Hill, but actually viable (since trying to crossover from high fantasy to/from oddball Sci-Fi to/from Wild West really fails from the get-go).