when we had geese as a kid, I remember the African / Heavy African distinction... we bought "Africans", which looked exactly like my current brown chinese. I have 4 in the yard now and they're a bit more slender necked and swan-like with a trimmer underline and slightly more upright body carriage than yours. I also have an "african" gosling about 2 months old, and it appears to have a somewhat shorter neck, proprotional to it's body, although it's still young and that could change.
looking at your photos, my first thought was "brown chinese", especially the adult standing to the left in the photo, but the one at the back, that's got the deeper keel and lower chest carriage... that looks african to me, although not as heavy as much of what you see in the hatchery catalogs.
the first photo here is what I think typifies the brown chinese - looong neck, more upright body, no pronounced keel, no dewlap:
http://holderreadfarm.com/photogallery/brown_chinese_page/brown_chinese_page.htm they're considered a medium-to-light goose.
this page has what I think of as typical of africans - heavier bodied, more keel, slightly lower carriage, shorter neck and dewlaps:
http://www.ashtonwaterfowl.net/african_geese.htm and they're considered a heavy breed.
interestingly, when I searched google for images of african geese, the pictures near the top look very typey, clearly african, and the further down the page you go, the more they look like brown chinese.
I'm guessing what we got as kids were not africans, but brown chinese, but the hatchery marketed them as african and heavy african. I'm pretty sure I was still seeing this distinction on at least one hatchery's website as late as maybe 12 years ago, but I don't see anyone advertising them that way anymore. Metzer Farms (in CA I think) used to have Super Africans which might be where the "heavy" africans went, although they no longer have them on their website.
One of the reasons we got the chinese, and why I still love them aside from their grace, is they absoLUTly will tell you when someone enters your yard.
They can be agressive, we don't handle ours much or make pets of them because we want them to alarm. One way to keep them from getting overly agressive is to make a general practice of herding them every time you're near them. eventually you won't have to do this, but it's a way of setting dominance. I just walk at them directly until they move off a few feet. if they don't take me seriously, I spread my wings and move a bit more briskly. if my arms aren't getting it done, I put on a rain slicker and use that for wings. Basically I just want them to respect my space and it doesn't take long to make myself understood. of course, the rules need to be re-taught when they start breeding or have young'uns to protect...
anyway, whatever they are, your geese look beautiful and healthy.