Could you elaborate on this? I use TKE in Vim mode every day and haven't run into issues with supported Vim motions. What motions did you try doing? Tcl/Tk is usually pretty difficult to crash.
I recall that there was an issue in Tk in regards to the wordstart/wordend index adjectives (which the 'b' command uses); however, I thought that was an issue with 8.5 version of Tk. What version of Tcl/Tk are you using? If you go to the About window within TKE, it will show which version is being used.