David, I can't doubt your interest in the medieval and renaissance lute, it is obvious. But I question your interest in music as such. The Chieftains (an Irish ensemble) have a video called Water From the Well. They use a Spanish (not classical, nor Flamenco) guitarist in one of their sessions - the Flamenco strum and the chorded left hand - and fit him into the Celtic session. It spices the flavor of that piece. Bluegrass I know well, and have a TV recorded video of Chet Perkins final performance, where Mark Knopf of rock guitar plays a real guitar behind him. Bluegrass is to me acoustic intruments - fiddle, mandolin, the guitarist as an incompetent chorder, and maybe a gut bucket (or if they are an affluent group a bass fiddle), plus the banjo over all, but it is the music that yet defines it, Flatt and Scruggs as a twosome, some of the songs I ply solo on the mountain dulcimer. It is the sound, not the instruments.
The most definitive of the old Irish is the singer. The Irish bouzouki isn't a factor. (BTW, the bouzouki is Turkic, but very similar to the balalaika). Sasha Polinoff, Theo Bikel and I have performed together (mid sixties) with Sashka on balalaika and Theo and myself on guitar. I totally disagree with your premise. The form of the instrument may drive the way it is played, but the music drives the player. I find the thrust of the messages on this list to be rather narrow in the conception of music (but I do hope I remain welcome here, I have much to ask you all about the lute music). It can be a pleasure to take the same piece and sequentially play it on different instruments in differing styles. Much of melody has been around for a long time, and has been used over and over again. It is the treatment that changes it (yup, anathema to the strict renaissance lutenist, but some things were played in different ways, trust me). I can't think of a better sound than the old style a cappella singer in Irish (I'll not give the Gaelic words), until I think of a lute working a simple song, and then I have to add a harp as a song player, but then there are the Scot's pipes that make me march and cry, but then it could be a Vivaldi orchestral piece, or my own group of fifty years ago singing the three part motets of Lassus and Palestrina. Hell, my musical education is incomplete until I play the lute, and if my "lute" isn't traditional in shape or details I'll yet play the music. (And I might mention, the hard fretted fingerboard of the one I'm making isn't a fixed thing, I can always plug the fret slots and make it a free fretted instrument with tied gut frets. I'm thinking about that.). Best, Jon