Hi Dave,
Been a long time, way too long. I hope all is well by you. I began adding Middle Eastern drums to my "arsenal" over 20 years ago and I play more darbuka than congas lately. Nothing like the sounds of congas and bongos, and I keep playing them, but must admit darbuka is easier to carry around.
Also must admit I'm not sure of the difference between darbuka and doumbek... in the Middle East I hear darbukas mainly called as such but also referred to as doumbeks and even tablas... the drums' names, like playing styles and rhythms, seem to vary between areas, even though many drums and rhythms are basically the same internationally... ie. "malfouf" in the Mid East, "funga" in parts of W. Africa and "ragamuffin" in the Caribbean are essentially the same rhythm....
Hope you enjoy this clip of soloing back and forth in a 7/8 time, with a bro of mine on djembe and me on a giant daholla (bass darbuka) made of clay with goatskin head:
http://www.youtube.com/watch?v=biEob61H9KU