I must have a look, as far as I remember there was a good discussion on napoleon-series.de on this topic, the Saxons, at least the soldiers and NCOs were quite disgusted with Boney already in 1812 - then even worse in 1813 when they had to see their country getting ruined by the war - also the demolition of the bridge across the Elbe at Dresden caused a lot of uproar.
So there was an undergoing erosion - the soldiers however, in case of not being enthusiastic would do their duty despite having to fight for a merciless tyrant destroying their country - the defection was lead by officers.