I love Pie Menus too, and I guess I should work on fixing the bugs I have found or just report them but most of them are already reported. 
Now to throw around some suggestions…
First,
Why not assume all devices to be warpable, and just remove common artifacts.
Also warping would have varying affects based on input device parameters like probably resolution, sensitivity, multi touch, and even the OS settings.
Second,
I think a more organic or dynamic design for Pie Menus will be better than hard coded ones, so that it makes use of the extra screen space, some have, or just make itself scarce if the screen space is low. Adjustable for the Mouse speed? Probably even have support for multi touch if the device supports it.?
Third,
I believe allowing high customizability and ability to create new Pie Menus on the fly is indispensable. It just makes the whole workflow feel soo much more personal. And I don’t want the user to have to know how to code to do it. This was a big problem when I help my friends learn Blender they couldn’t make new Pie Menus cause they weren’t good with coding.
Also,
As for reference Code Base, try
This is JacquesLucke’s Nodes Playground Branch it might have some graph stuff in the commits you might want to see.
I only recently got started with the Blender Development so not sure about the code base yet… 