Post resor, OP delade sin erfarenhet i kommentarer (som inte kan sökas och kan försvinna):
It was quite full on a Monday, but everyone had seats. I tried to choose seats so that they are close to the luggage rack; or they are close to a location with back-to-back seats. That way I could put the luggage inbetween the opposite-facing seats.
Lyon -> Frankfurt was more crowded than Frankfurt -> Dresden (up to Strasbourg)