In your awesome example code, the code to get the VBR will crash on an 060 with Caches enabled because the data you specify as the instructions to execute in supervisor mode will never actually be written to ram. Its held purely on the stack (and in cache)

Please add...

CacheClearU();

immediately before

vbr = (APTR)Supervisor((ULONG (*)())getvbr);

and code will run even with 060 MMU+Caches enabled.