I was able to modify the original Ableton sync project so that the mixout cues are no longer needed and it has the ability to mix any scene to any other scene (or part of a scene).
The mixout column is no longer in the scenes table. It's using the $SCENE_NEXT variable to mix into the new scene so your mix time is dependent on the Ableton TD sync clips quantize setting and a trigger chop in the mixer comp. The trigger chop controls the speed of of the crossfade and is currently set to just under a bar length. So if the clip quantize is set to a bar (or global) you should trigger the clip just after beat one to get a 1 bar crossfade. If your too early or two late you'll get a jump in the crossfade. This can be avoided by making a shorter envelope.
If anyone else has any ideas to improve this that would be great.