@ downix

Indeed, now I am quite confused. I read somewhere that ARM's big endian mode would basically just be the possibility to load big endian data correctly (i.e. e.g. word order is correct), but addresses themselves, representation of internal states and counters would be in little endian schem. Now I read the "programmer's model for Big_Endian ARM" from arm.com and from that document I understand it that way again, I originally thought it would be.
ARM >= ARM6 can be operated in true big endian mode. But as said, I *am* confused now.
My take on it is as follows:
What would happen if a 68k app running on a hypthetical MorphOS ARM with transparent 68k emulation would try to access, say, 0x00000004? Would it get a pointer to exec base or would it get elsewhere? If it gets some other than the exec base pointer, then I guess a 68k (or ppc) emulation is in some serious trouble. If it works, fine, then there is no endianness problem. But I was not able to disentangle this problem myself. I cannot predict the behaviour of ARM from the docs I read (I definitely don't claim to have fully understood what I read!!).
If you or someone else can enlighten me in this case, that would be appreciated very much.