1) Ubuntu and Debian do in fact have independently maintained repositories, with different update schedules to popular software. That makes me a fan of Debian over ubuntu for that reason alone.

Package: blender (2.45-5)
http://packages.debian.org/unstable/graphics/blender

Package: blender (2.44-2ubuntu2)
http://packages.ubuntu.com/gutsy/graphics/blender


2) I HDD-installed Knoppix 5.3.1 on a junk, old computer and am apt-upgrading. No smoke yet.


3) Remember, the problem with audio upon HDD installation is a bug that goes all the way back to 5.0.
The workaround is shown in Bug #10 here:
http://www.knoppix.net/wiki/Bugs/5.0DVD

Perhaps the fact that the bug is unfixed since 5.0 is a reason not to HDD install after all.