For two weeks I've been using Mesa-6.5.2-git-head, and it seems stable now on a
KM400 Unichrome: it doesn't lock up the machine any more.  But it makes a few
small rendering mistakes, which in one case (blender) makes the app unusable.

The observed errors:

In 'glxgears' the content breaks out of the bottom of its window.  See first
attachment.  This might be related to bug #9210.

In 'blender' the menus are all black with here and there horizontal stripes of
random data.  (With Mesa-6.4.2 the menus are lightgrey with black text.)

In 'bzflag' the horizontal surfaces of buildings under certain angles show dark
artifacts.  And flags that are not close by lose their top half: at a certain
distance narrow vertical black lines appear that quickly grow wider with
increasing distance, until the top half is fully gone.  See the four other
attachments for examples of these artifacts and cut-off flags.

In 'slune' the borders between textures are jittery: triangles flipping back and
forth between one and the other texture.