I think the N8VEM 6809 host processor is the only
system I am aware of other
 than Dave's homebrew that is running CUBIX.  There maybe some other homebrew
 systems out there too I can't find them after some searching.
 Thanks and have nice day! 
I've corresponded with a number of people over the years who have built up
Cubix systems - probably a dozen or so... it's definately not mainstream,
but there has been a small following.
Btw - anyone wanting to fool with the 6809 from a software point of view,
including running CUBIX, can simply load up my D6809 simulator ... it will
happily run on an old 386/486 DOS PC if you like (you can put it in a box
and pretend it's a 6809 system :-)
Dave
--
dave09 (at)    Dave Dunfield
dunfield (dot) Firmware development services & tools: 
www.dunfield.com
com            Collector of vintage computing equipment:
               
http://www.classiccmp.org/dunfield/index.html