AmigaOS uses cooperative multitasking with a preemptive scheduler. Where it falls short of the definition of preemptive multitasking is memory protection and task protection. Without both, you're going to have badly behaved programs trashing daemons, other programs or the kernel itself. On UNIX, Windows NT and Linux, for example, the worst a badly behaved program will usually do is coredump with a segmentation fault, vs on the Amiga where it will lock up the system or send it into a guru meditation error.
AmigaOS is pre-emptive and not co-operative. You can't just redefine the terminology.
On Unix, Windows NT & Linux you can take down the entire machine from software.
I would quite like to see a modern x86 or an ARM on an A1200 accelerator card.
It's kinda interesting to have AGA for an A500, although I don't know if I'd actually buy one.
