Hi Thomas,
I will definitely keep you posted on using Natron. Seems that much can be done with .png files in Natron.
But, Knowing myself, I will need to encounter something I can't do in Premiere before getting into Natron.
There is nothing worse than having a project that is super complicated from a production stand point.... That is, when one minor change cascades hours of hassles in multiple programs.
Best,
Rick