There are many ways to use an open / chordal tuning and still take advantage of the sustain offered when playing in the home key. I would call Oswald's writing in the Divertimenti that Rob has described idiomatic, meaning that it fits the open-tuned cittern in a way that it doesn't fit other instruments/tunings. It also fits in terms of the size of the instrument - with such a short string length, playing two voices can be tricky.
What Rob has said about use of dissonance is the main reason I use so many campanella-type fingerings, and this is something else that goes well with the short string length, as well as with the wire strings. By the way, Oleg Timofeyev's contribution in the cittern book I mentioned is in part about the relationship between the 18th-c cittern (a.k.a. English guittar and Polish guittar (!)) and the Russian 7-string guitar. Doc To get on or off this list see list information at http://www.cs.dartmouth.edu/~wbc/lute-admin/index.html
