Yup, I ran KDE myself. I experienced some color weirdness with my PicassoIV, but it worked great with my CV-PPC.
Perhaps some lagging, eyecandy should be avoided. I used Debian (APUS) primarily for running the web browser 'Opera', in order to gain access to Amiga-unfriendly websites.
But be warned: I had to do a lot of configuration by hand, by editing the 'XF86Config-4' file with 'vi' (a somewhat awkward text editor), in order to get mouse support, a usable keyboard layout and decent video modes.
So, if you have the patience, go for it.
a bootstrap line for running the installation should look approx like this for a CV-PPC/BV-PPC:
"bootstrap --apus -k vmapus -r ramdisk.gz root=/dev/ram video=pm2fb:"
I had some problems with the latest kernels, the newest one I managed to get working, was v2.4.20-1.
Good luck, and if you need some help, don't hestitate to ask.
-Paul