As KDE 4.2.4 was just released I became really eager to try it out. I have tested KDE 4 series earlier. The first version, 4.0, was bit of a disappointment. 4.1 and earlier versions of 4.2 seemed solid enough for casual use. MEPIS is still based on 3.5 by default. More here
It is possible to update MEPIS to 4.2 by adding some experimental repositories to /etc/apt/sources.list. That’s what I did. Debian experimental repositories work out of box. I managed to install the KDE 4.2 packages after bit of wrestling. To cut the story short I ended up system in which I could not get into graphical login screen. It was time to give openSUSE a go.