AROS. Nuff said. We're all in favour of memory protection, and some of us even to the point of burning all bridges to classic amiga. Why? Because we believe in the AmigaOS, not focusing on the OS API and old times. We like the elegance in simplicity, without mentioning what's under the hood (even though, AROS, is very much alike AmigaOS underneath the hood...)
What you are looking for is called AROS. Just help us out! We need your help. We're Open Source, and we're AmigaOS 3.1 remade.