Welcome in the minty community.
I solved the problem as follows: after LMDE brought no updates since about September, I installed LM12 KDE. So I got again a good «work horse» (I also have still Kubuntu 10.10 as a backfall) and Sabayon as a test. And once, when LMDE KDE is released, I will install it on a third partition and hope to bring then this version up to become my work horse.
To mange this, I have practically no own data in the /home partitons, just what is here from the system. Each Distribution has its own /home and there is – on a separate hard disk – a few (NTFS) partitions where I store all my data. So Partition for Video (photos, films, snippets), for Audio, for Data, for Joint Data and for Backups. NTFS because then I have never problems with rights.
Into the Joint Data come the Mozilla profiles, all the fonts, the Gimp resources, the channel listings for Kaffeine etc. This guarantees, that I have on all plattforms the identical look. (I never understand why Debian puts for example fonts into three different folders: /home/user/.fonts, /usr/share/fonts and /usr/lib/share/fonts, same goes with Gimp and Mozilla.)