Considering how Germany was an urban industrial society, I doubt too many Germans would have been willingly attracted to Africa of their own volition. I can see some adventurers and more die-hard Nazi fanatics wanting to try it out, but unless they were forcibly settled there, the Germans in these territories would probably be few in number. To really succeed they'd have to rely on ethnic Germans from poorer regions (Bessarabia, Transylvania, Volga Germans, etc.). However, with little experience in tropical or even Mediterranean farming it would be interesting to see how many would succeed.
Take the French experience in Africa, very few French settled in their own African territories, due to having a relatively comfortable life in France. The result was that Algeria's European population was only 40% of French origin, and most of these were from Corsica and what was then the poorer south (Languedoc and Rouissilon). In Tunisia, over 2/3 of the Europeans were ethnic Italians. However, the French found no shortage of Spaniards, Italians and Maltese form the poorest regions of those countries wishing to settle in Algeria. However, most were from regions only a few hundred miles away from Algeria, so the climate was largely the same. In the other French colonies, ethnic French tended to be administrators, civil servants and representatives of metropolitan businesses. In French West Africa too the French were outnumbered by Syrians and Lebanese.
In contrast, the Italians had success in settling large numbers of Italians in Libya and Italian East Africa in a short time. The European population in Libya shot up from 66,525 in 1936 to 128,264 in April of 1940. In East Africa the European population went up from 5,819 in Eritrea and Italian Somaliland in 1931 to 151,567 in all of Italian East Africa by March 1940.
However, one has to remember that Italy was much poorer than Germany (especially in the South), Italy's birthrate in 1940 was comparable to that of Germany in 1920. A poor landless Italian farmer from Sicily was probably more likely to be illiterate and willing to take the risk of moving to an unknown area for with the promise of free land. However, the Italian experiment of demographic colonisation in Libya and East Africa lasted less than a decade, so it's hard to evaluate the long term results of the policy. Also, emigration-wise Italy's large emigration until the 1950s was comparable to Germany's situation 40 years before.
Portugal too mimicked experimented with demographic colonisation in Angola and Mozambique beginning in the 1910s on a small scale. However, the large-scale settlement projects were only underway beginning in the 1950s. Portugal was even poorer than Italy, and its birthrate in the late-1960s was the same as Northern Europe's before World War I. Therefore, the country had no shortage in prospective colonists and selected them carefully. However, even though these projects continued right up until 1974, the government found that many of the settlers abandoned the land and moved to the cities and towns where they could obtain wage employment. Most however preferred to become small traders or setup small businesses on their own.
In the end, even with the coercion of the Nazi state, I don't believe they'd have much more success in founding successful agricultural colonies anywhere, much less Africa. Most people want wage labour, and unless the land holdings were very large commercial farms, they simply wouldn't provide enough in income for a former city dweller to be satisfied.
The most successful attempt for ther Germans to colonise would have been emulating the British model in Africa (Kenya, Southern Rhodesia and South Africa). That is attract middle to upper class settlers (many from the armed forces), give those with the capital to develop land large tracts of land where they can employ lots of Africans to grow cash crops.
However, the main attraction of Africa would be attractive "garden cities" like Salisbury in Southern Rhodesia where large numbers of Germans could enjoy a higher standard of living than that found in Europe. That being make Africa's cities and suburbs attractive alternatives to living in Bremen, Frankfurt or Hamburg. To this day large numbers of British still move to Australia due to the better climate and the ability to enjoy a lifestyle that would be much more expensive in Britain itself (though in recent years Australia's real estate costs have made this less attractive). The same was true for Brits moving to South Africa and Southern Rhodesia.
This pattern could have been emulated in the German colonies. Firstly land would be cheaper and homes most likely cheaper to build than in Germany itself, due to low cost labour. A single-family home with a swimming pool, a large garden and automobiles would be the lifestyle offered in German Africa to a middle-class family from the crowded German cities. To top it off, a plentiful pool of cheap domestic labour to cook, clean and tend to the garden exists. For many moving to Kenya, Rhodesia, South Africa (and the Portuguese territories), this was what made Africa attractive, the suburban lifestyle based around the automobile available to middle-class European families. That in my opinion would have been Germany's only shot at attracting a large German population to Africa.
