MP on the amiga is a more or less academic discussion that interests the (few) developers every now and then.
I wouldn't let any Amiga powered on for weeks with lots of software running and important data unsaved. This isn't an academic discussion...
I wouldn't mind letting powered on MacOSX, Win2K+, Unix opened with lots of important stuff unsaved. Cause unless there was a powercut I know my data would be back when I'll get back.
I don't want to have to choose the software I run because it may make me lose my work... nor do I want to wait before my HD led is off before powering my computer off, nor do I want to have to check I have enough graphics memory before running a (graphics) memory hungry software because the OS isn't capable of swapping: this is the task of the OS, not mine. The OS should (and will) take down any application trying to write outside its memory mapped, the OS should close all apps and power the computer down when no app is writing to the disk, and the OS should automatically swap memory for my apps...
This was acceptable 15 years ago. I think it's not today. Much like monotasking OS isn't acceptable, even for a phone... Would you use some DOS-like monotasking OS today ? don't you think having a GUI or not is an academic discussion ? after all you can do everything you want with just a simple console, right ?