OK. I think the best thing to do then is to briefly mention in the manual that if the user has problems with the full KX DVD iso they also have the option of using the PPAs with various other Ubuntu based distros. Of course, Ubuntu has its own install docs already and there are hundreds of Ubuntu-based distros too but I'll likely just mention Mint and Ubuntustudio as some of the alternate Ubuntu spin-offs they could try alongside the KX netboot iso and vanilla (Gnome/X/K/*) Ubuntu as a base from which to add the PPAs with 12.04 based versions being recommended above the later ones. OP updated.
I disagree with the focus of just saying "if you have problems." KXStudio, as falktx envisions it, really does support these other options. I would neither endorse nor avoid this in the wording. The simple thing is to say essentially, "this documentation focuses on those doing a fresh installation from the KXStudio ISO, but those who prefer to use an initial or preexisting installation of an Ubuntu-based distro such as Ubuntu, Ubuntu Studio, Linux Mint, etc. can use these PPAs by following these instructions:"
What I'm saying is, I don't think we should tell those who want to do the ISO that they should try this, that's not the purpose. The purpose is to acknowledge that it is an option. Some people may already have a system installed, for example. We acknowledge that this exists, and that's enough so that people know it is an option if they have trouble. It's just a side acknowledgement. It's an acceptance that just because we're aiming at someone installing a fresh ISO, this does not mean we are sure that is the only reader, so we're acknowledging the existence of other readers but telling them that they aren't the focus.