Meanwhile I use MyTourbook 11.8.2 on Ubuntu Natty 11.04 and I am happy with it since more than 2 years.
One issue that came up recently: when I open the Tour Editor to edit the (top-most) "Title" textfield, then the Tour List frame is refreshed upon every keystroke. My tour list contains a few hundred tours and my 2GHz Centrino is not ultra-fast, which limits typing speed to about 1 letter per sec! And even worse: if I type too much ahead then the cursor occasionally jumps to the beginning of the title and continuous to emit the letters there.
Other textfields in the Tour Editor are not affected. And I am not 100% sure, but my earlier MTb 10.x.x on Ubuntu Lucid 10.04 did not have this issue. Perhaps this has to do with the fact that since Ubuntu Natty I use OpenJDK because Java of Sun/Oracle is not available anymore through the Ubuntu package sources.
I am software engineer from near the Zürichsee (not far from you, isn't it?) and I'd be glad to help solving this.
Thank you for MTb!