I am in the process of writing up our adventures
... stay tuned :-)
It's generally quicker to do a new full install unless it's just a single app. For instance we upgraded Libreoffice once to get a later version that cured a nasty bug. In our original images we did Nvidia 'the hard way' but that makes doing a full upgrade very slow as you have to do the Nvidia thing again on every machine, now we just do it via the repos, you might not get the absolute latest version but it makes life a lot easier.
The only things you have to do before you upload the image is remove the entry for the network from udev otherwise when the imaged machine comes up it has two networks a 'phantom' one from the original machine and the actual one that is tied to the mac address in the imaged machine. The only other thing we do is the disks/fstab by label rather than by GUID or UUID this is not the Suse preferred way as it means that the machine probably won't boot if the hardware changes but In our environment I see this as a bonus.