Interesting project! In a past life I worked on a project that used PyQt; on the one hand, I enjoyed using a very mature toolkit with lots of features, but on the other hand the Qt way of doing things often clashed with the Python way of doing things and I longed for something simpler.

What's the OpenGL situation like? The project I speak of used some hand-written OpenGL shaders. One of the things I appreciated about Qt was that you could ask it for an OpenGL window, and it just worked. (For values of "just works" that include cursing for hours at a black screen but eventually convincing it to draw triangles.)