Ubuntu - not kosher?

[Brian Astill <bastill@adam.com.au>]

I have been trying Ubuntu, and am impressed so far (I much prefer KDE
and its tools like Kontact, but ..  )

Question. Is Ubuntu/will Ubuntu become .. somewhat like Knoppix.  ie an
excellent tool and nice distro, but neither one level nor another and
therefor fraught with danger if you want to upgrade something
substantial or Knoppix itself without breakages?

Ubuntu _does_ promise an upgrade path of the main system, so perhaps all
is well in that area?

Opinions welcome.

--
Brian