Whats wrong with the ABox ?
You CAN run amiga software, but
you dont have to. Nearly every day new
software comes up written/ported for MorphOS.
And MorphOS is the responsive part you seem
to look for ... Just because it's somehow
compatible to amiga it does not make MOS old or
slow.

When you just want to run Linux you're stuck with
another bloated OS like windows. MorphOS is the right
choice. And MorphOS needs the ABox (atm) ... :D