- Laire rewrote/ported MUI3.8 to PPC (ca. 2001) thus creating MUI3.9 - Stuntzi licenced that version Hyperion including source for compability reasons only (ca. 2002) - Stuntzi with the help of others updated it to early 4.0 versions - Stuntzi had some fallout with Genesi over outstanding payments (wether he wanted to be named on morphos.de hijacked by Zapek is unknown) - Stuntzi uses/used a great deal of his freetime for extended bicycle tours across the world, seriously reducing the time he could spend on MUI - Stuntzi objected to the recreated MUI4 not needing a keyfile (if he objected to the whole thing is unknown)
What we also don't know: - how much work did Stuntzi invest in MUI in the past ±10 years - how much of MUI4/5 has been done by other team-members - do those team-member have in stake in MUI's copyright, or is it still 100% owned by Stuntzi
In essence, all we can say is that NotMUI4 isn't 100% compatible and versioning is atleast confusing if not misleading.