Thought I would start a thread to gather info on what method(s) work to 
upgrade from 3.5.13.2 > R14. I did this from  konsole in an x session.

System: Debian Squeeze LTS, AMD64. I changed my sources list to the 
nightlies. Ran "apt-get update".  There is one package to be removed, 
many new packages to be installed and fewer to be upgraded.

 'apt-get upgrade' will not install the new packages, they are held 
back. I used 'aptitude upgrade' and the resolver figured out all the 
depends, new installs, upgrades and removal. 

Almost perfect, better than any previous upgrades. A couple of  things I 
noticed is my desktop wallpaper was set at the default, I like 'alien 
nights' :-)

Ending my current session via the logout dialog drops me to a cli, I 
have to 'restart tdm-trinity'.

I did test this on a vm (cloned) I have for legacy support purposes. 
Real hardware may be different.
-- 
Peace,

Greg