I haven't heard of Mbenji Blues before. From a quick google search they look quite nice.
The only other elongatus I've kept was the "Chewere". IMO they are one of the most stunning. I originally had some nice F1s lined up from Canada, but that fell through. I stumbled on some locally, but wasn't happy with the quality (markings on the side weren't crisp diamonds, but more of a "diamondy-stripe" so I didn't keep them long nor bred them.