As many posts showed, Solaris is NOT the most "advanced" OS.
All pro-Solaris posts insist on reliability (granted), and superior
support (valid only in a very few countries).
"Advanced" has a meaning of bleeding-edge which Solaris definitively is
not.
In fact I suspect that the recent commitment of Sun to OpenSource is
recognition of the superiority of the OpenSource Model in matters of
fast, research grade, development of an OS.
In house refinement for reliability by Sun could then give them the best
of both worlds.