Great thanks for the inputs... I think I will keep my Aeroplan rather than join Miles and More.. One of the things that add complication is the fact that with Miles and More, Star Alliance gold on LH is only granted to LH Gold (equivalent of Super Elite = 140,000 miles for German residence). I doubt that I will be able to make the miles to get Gold... but can easily achieve it on Aeroplan.

Most of my long haul flights from Germany (ie. to Canada) will be on Business class.

As a BA Gold flyer as well, I will apply for the BA Credit card in Germany.