> Any previously-owned Mac mini PPC will [...] run twice as well.

In case "well" also includes "fast":
I think it's a save bet to say that the X1000 will run faster than Mac mini PPC.

> And not be a pain in the butt with system building and set-up

According to A-Eon, the X1000 will only be sold as complete system, i.e. full setup including OS4 pre-installed.