Do I get this right, you want to port a plan9 GUI to linux framebuffer for performance and low security? And then you want a potential X compatibility layer on top of it? And you want to trust your applications more? Do you think they feel bad if you don't trust them enough?
You could try http://www.omgubuntu.co.uk/2012/03/how-to-easily-skin-ubuntus-unity-desktop/ first?
