I wonder if KDE stability is related to i18n/l10n. I am running desktops in German and KDE crashes for me all the time on freshly installed machines before I even could touch settings. (I tried a lot of KDE versions over the years, from stable/mainstream distributions like Debian, Fedora and Ubuntu). Besides the constant crashing I missed a mail client on the level of Evolution or Thunderbird when I tried KDE.