I can't add any new thoughts to this thread, but I can perhaps add some weight to existing thoughts.
I have had a lot of taxidermy done; both at home (Canada) and in Africa, using several different taxidermists in Zimbabwe, South Africa and Namibia.
Based on my experience, most African places will do "OK" work. To me, OK work is a decent mount that will look fine on a wall, provided it's not next to "really good" let alone "great" work. You won't be embarrassed by it, but no one will rave about it either. Perhaps there is someone in Africa who can do that kind of "wow" work; if so, I haven't found them or heard of them. Do not be taken in by the "we know the animals better" argument. Any good taxidermist in North America will have experience with African animals, and what he lacks, he can figure out. What matters is a commitment to quality work, not familiarity. I have never had to junk a mount done in Canada, while I have scrapped far too many mounts done in Africa to mention. Equally, when people look at some of my mounts, they can immediately tell that some are different. Great work just really jumps out at you - the animals look alive.
The real difference between North America and Africa is in the process. In Africa, taxidermy studios are generally owned by a qualified taxidermist, but most, if not all, of the work is done by local people who might have some training and experience, but it will vary greatly. In this case, you rely on the African taxidermist's commitment to quality control, rather than to his own skills. In North America, most taxidermists work in places with very few, if any, staff, and they do the work themselves. I believe the North American process is inherently better, but if the African quality control is good, and the workers are experienced, then it doesn't have to be substantially different. But it's never worked out that way for me!
Having said that, I believe a good African studio can do a better job of some unusual things than can a studio in North America. For instance, I believe it is easier to tan very heavy skins in Africa - the tanneries do have more experience with hippo, elephant and giraffe skins, for example. I have had challenges with these at home. Secondly, for things such as gun bags and furniture, again, the Africans may not only have more experience, but labor costs will be important and you aren't looking for a realistic mount - you just want great furniture. I had a trunk made in Zimbabwe from a hippo I shot, along with a small contribution from a giraffe. I now use it to store my hunting clothes, and it is beautiful. I have no doubt it would have been difficult to make in North America at a reasonable price.
The upside to using Africa is that even though you will likely pay more for shipping (mounts being heavier and bulkier than dipped and packed specimens), you will save on the taxidermy itself, so all in all, it will cost you less to have the work done in Africa. Sometimes you just have to go with what you can afford. If that's a real issue, no need to be embarrassed about it - there are plenty of African places that will do an OK job for you - you can find some on this site. But if you can stretch to the higher prices, I don't believe you can beat the quality of a North American product.
Hope this helps.