One of my projects over the past year without gigs has been to finally create and work on playing this fretless bajo sexto. I've been playing (trying to figure out) bajo sexto since 2004. That's kind of a long story. I've wanted a fretless one for a long time, and finally got around to doing it this Spring. (Thanks to the Fretted Instrument in Amherst for putting on the beautiful brass fingerboard). I've been playing it a lot, and have a lot to learn.
The form of this improvisation is a sort of Americanized raga alapana. My main instrument of study has been the Saraswati veena, and much of my playing is modified from that technique and instrumental tradition (Karaikudi veena). On paper the structure of raga Shankarabharanam is analogous to Western major. In reality, not so much. I'm definitely in major here, although there may be touches of Shankarabharanam and maybe even Yamunkalyani.