I work all over Africa and take regular biking trips to Morocco, in 5 years of working in some of the world's "most dangerous" countries, I've never had to deal with anything worse than a bit of police corruption [white man tax] and the odd mugging [not of me!]. In all honesty, countries like Nigeria, Equatorial Guinea, Angola and sometimes Ivory Coast are the ones you need to be thinking about..[Basically the Oil rich nations are the ones you are most likely to encounter hostility] North West African nations are generally pretty easy going and accommodating.
Yes, you have the issues of isolation and potential disease / medical care issues, should you get involved in something nasty, but I honestly believe the smaller scale rallies have nothing to fear from the "threat" of instable nations. Please remember that these countries have very well trodden paths for European adventurers and when passing through villages etc you very often receive a warm and excitable welcome.
True, in the bigger cities, you are more likely to encounter a chance of aggro from a minority of locals, but as a rule, I would not hesitate to join any North African rally, or get on my bike and ride to Cape Town from London!
'10 KTM 450 Meca Rally,'09 KTM 250 EXC, '98 CCM R30M Supermoto prototype