The Garmin 276 is a very capable, very modern and fast GPSR. It was designed primarily for marine use, but does a very good job when in automotive mode.
It's probably a more expensive and more capable GPS than you need for your trip. The big issue you have to consider with GPS use in lesser developed countries is the availability of cartography for that country.
All Garmin autorouting GPSR's share the same basemap* (the map that is burned into the GPSR and cannot be changed). This means that the basemap in the GPS V and the basemap in the 276 are the same.
Any GPSR - even the simplest one designed for kids to play with - will tell you where you are with great accuracy. In that respect, for auto travel, they are all the same.
If you cannot get detailed cartography for the places you are going (and that means any part of Africa, except for urban areas of South Africa), it's kind of pointless to get an expensive, autorouting GPSR. You might as well get a simple, inexpensive one, because you will be relying on paper maps, and the only value of the GPSR will be to confirm your present location.
I own a 296 (the aviation version of the 276) as well as a Garmin 2650. These are the two "top of the line" Garmin GPSR's. Although they have amazing capabilities in Europe and North America, they really don't tell me much more than my latitude and longitude when I am in Africa. I could get that with a $100 used GPSR.