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. There is a fork known as DanumLinux that provides 4.2, though.
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.
I have used openSUSE 10.2 before. It has proved to be a solid operating system except for some occasional Firefox crashes due to opening a file dialog. The installer managed to retain the partitioning I set up during the MEPIS installation. Overall it worked really smoothly. It's hard to find anything to complain about openSUSE's installer.
After installation I added some needed functionality (ie. media playback, KDE 4.2.4) using "one click install" links found on the net. Things worked out quite smoothly. I had minor problems after trying to install fglrx driver for by graphics card according to instructions given at http://en.opensuse.org/ATI. I managed to revert back to open source driver by logging in as root and using "init 3", "SaX2 -r -m 0=radeon" (that's a zero!) commands.
I managed to get by DVB-T card work yet again by copying the missing firmware in its place as described earlier. I also had to change the keyboard layout to "Acer Laptop" as in the case of MEPIS. For some reason the artefacts seen in DVB playback are much less severe than in MEPIS and Ubuntu. I suppose openSUSE must use a newer driver or something. :)
If there is one thing I favor openSUSE over MEPIS, it's the network manager. It's really simple and nice to use. Setting things up worked out smoothly unlike in MEPIS where it took a bit of "try and see if it blows up" to get it work.