Interesting blog. Thanks for the link.
I have to say that, hanging out around Berlin's African community when I was still married to my ex from Sierra Leone, I noticed similar problems:
Educated members of the community all spoke fluent German and fitted well into the local society (often in good jobs, like hospital doctors, architects, engineers or nurses). They often had German partners and came to Europe in the 1970s-1980s as university students and stayed on after their graduation.
On the other hand, there were quite a few youngsters (mostly young men) without any education, who came in the 1990s as "political refugees", who had a strong sense of entitlement and wanted to keep seperate from the local population in their own, exclusively African, community.
I also noticed that most Africans I met were very religious, either Muslims or Christians.
Je Suis Charlie et je suis Ahmet aussi