I know you are going to hate this response, because it's going to be a yes and no response
I was there early this year.
I had gotten my visa in Yaounde in Cameroun. But because there was an english couple traveling about a month or so behind us, we asked at the border if it would have been possible to get a visa directly at the borderpost. The answer was; yes, we could have. The french language barrier was (and still is) a problem for me, so I could have misunderstood the answer or he could have misunderstood the question. And to be honest, the "yes" answer seemed more like "yes yes...now get out of my border post so I can get back to my lunch" more than "yes, that would definately have been possible sir. We look forward to welcoming your friends".
I just thought I'd respond to your question since no one else had. If I had to wager money on it, I'd say; get your visa in Yaounde. Unless as you say, you hear from someone who has actually gotten one at the border.