I have had similar experiences with Kivy. I previously developed a simple game with PyMT[0] relatively easily, so I was very excited when Kivy came out. I had another project requiring multitouch support on a PC recently and decided to use Kivy and it immediately crashed my window manager every time I tried to run it which turned me off pretty quickly.

I ended up doing the multi-touch UI in JavaScript and HTML instead. It felt much clunkier to work with, but I wasn't comfortable with wrangling Kivy's instability for the rest of the project.

[0] http://cleichner.blogspot.com/2011/02/multitouch-project.htm...