Personally, I use Apt (w/Synaptic) for any updates outside of the major package sections like KDE or Gnome. I do this because I like to have access to a lot of the third party packages and you just can't do that with YaST to the same extent that you can with Apt. So, basically I use SuSE's supplemental update mirrors to notch up on desktop environment versions, and then use Apt for whatever else I desire to include.
However, this is NOT a recommendation as third party packages can and do break base systems. I've done it myself on several occasions. I would only advise that similar actions to mine be taken by people that do not mind fixing things that used to work properly (that's the best way I can phrase it I think). You will be doing this.
That said, here is my current sources.list from /etc/apt/.
It hasn't demolished anything recently.
# Uncomment the line below, in case you want to use SuSE's patch rpms.
# Read the information about patch rpms at http://linux01.gwdg.de/apt4rpm
# rpm ftp://ftp.gwdg.de/pub/linux/suse/apt/
SuSE/9.2-i386 update-prpm security-prpm
# A very basic sources.list line. Fastest repository first.
# Remove "base" in case you are behind a
# slow connection. Fastest repository first.
# Visit the server to determine which apt components are provided.
SuSE/9.2-i386 update suser-guru suser-scorot packman packman-i686 rpmkeys base misc kde suser-rbos suser-tcousin suser-ollakka funktronics security
SuSE/9.2-i386 base update security
# The list with all available components can be found at:
# Some components provide experimental software, select wisely!
# Consult the link above if you want to include uri's for src rpms