As you might be reading this Henrik, v0.6-908-g1cddc86 where you disabled ext/ins does indeed fix Persona 3 loading.
EDIT: Another bug which I though was unrelated that is also fixed is buggy dialog boxes when starting a new game. They were missing backgrounds among other things, but they are also fixed in v0.6-908-g1cddc86.
I hate saying this, but v0.6-909-g7dc75d8 has broken it completely with JIT, all graphics is garbage, although loading works... Turning off JIT fixes it. See attached screenshot.
EDIT: Another bug which I though was unrelated that is also fixed is buggy dialog boxes when starting a new game. They were missing backgrounds among other things, but they are also fixed in v0.6-908-g1cddc86.
I hate saying this, but v0.6-909-g7dc75d8 has broken it completely with JIT, all graphics is garbage, although loading works... Turning off JIT fixes it. See attached screenshot.