126.7:
it DOES matter what nationality you are - DFS prefers European controllers, because their licenses can easily be transferred into a German one.
In addition to that, you have to fulfill some requirements to receive a Security clearance which you need to have regardless of unit. That means, citizens of certain countries (e.g. some former Soviet Republics and some middle east and far east contries) will not be considered by DFS because of their heritage - it is sad, but the rules are made by the government and I guess, other countries have similar laws.
Hope to see some of you guys soon here in sunny Karlsruhe :-)