I have two or three Bembeya Jazz live LPs, one of which is from the Pan-African Festival in Algiers 1969 (where Archie Shepp's Live at the Pan-African Festival was recorded), I don't have them with me but I remember the sound quality being quite atrocious, which is understandable. I also have an instalment of their Discotheque series, 75 or 76 (?), some nice tracks on that one but I think it is mostly Bembeya Jazz as well. So I really can't say much about the label, though it'd be interesting to explore it. I wonder if there are there any reissues?
Guinean music is not really over-exposed, is it, I mean everyone can name a half dozen Malian singers but I'd be hard pressed to name a single Guinean vocalist apart from Mory Kanté. Sad, really.