I wasn't intending to compare the technique to conga playing - but the sound! I think it's perfect for conga players who want to add other kinds of sounds and tonal colors to supplement (or even stand in for) congas. It's that full, rich sound you can get from cow...
Also, since there isn't a lot of info. available - let alone teachers here in the West - I kind of think it's premature to talk about technique in a definitive way. (Just my thought; might be that some of you have far more experience with this instrument... from the source.) My other hunch is that it's been played by some people here in the US who are part of the "old-time" drum and dance community - and that's a small group of people, from the 1940s 'til today.
zack, nope - I don't own any of these drums yet, but they're on my very long list! (A bass djembe is going to come before these, I think.
Edited to add: I think there's plenty of room for playing any/all of these instruments in non-traditional ways while also staying true to the roots styles. I sometimes play my sangban like an Indian double-headed drum, with it across my lap; sometimes I just play one head, frame drum-style. You can get an amazing range of sounds on the duns with hands alone. I wouldn't play in this fashion for W. African-style playing, but as a percussionist (overall), I see huge value in the wide range of sounds/effects that can be used for non-trad. gigs and jamming as well as recording. (Not that I've got any gigs right now, though... wish I did.)