Hey drx. I have contacts with Michael Latham, the guy behind Eternal Champions. I'm just typing to tell you not to bother dumping any prototypes you encounter relating to the Eternal Champions series aside from side games. 

Mike told me that the Eternal Champions games were pretty straight forward in development and all prototypes are nearly identical to the final product. This goes for both the Genesis and Sega CD titles.

Also: the third title planned for the Saturn never made it past concept stages so a prototype doesn't exist of it at all.