This is a really interesting thread. I found this link which could be very helpful. It is a study from 2015 that analyzes the disparate implementation of direction 2003/109/ec by country. It is striking how differently different countries have implemented this directive, with Sweden, Portugal, Czech...
Have you heard anything back from the German embassy? I also have an EU long term residence permit issued under 2003/109/ec and am pretty confused about what advantages it gives in terms of moving to countries like Germany. I know Sweden makes it easy but anyone else?