Update: When being careful and not purging any KDE/GNOME "central" packages, plus checking the suggested purging solutions before committing, it seems to go fairly well purging ca 1.5GB worth of programs. It turns out that several of the problems encountered upon remastering 7.0.2-7.0.5, disappear if I write /home + /var to the new persistent image, taking up a few hundred megabytes there. I don't know what this is, maybe something with aufs - but at least it now seems to work like it used to before. One should note that this isn't that much of a loss in practice, as /var will be populated with apt data as soon as we start updating and installing packages. When these data are already written to persistent store in the remastering process, updating will not take som much extra space.