Is there any other Chikari tuning out there besides G(middle octave) - C(middle octave) - C(upper octave). I had heard of Debu Chaudhuri tuning in C (what octave?) - C(middle octave) - C(upper octave) Has anyone tried that? And is the first C in middle octave? Sitaratis, Inc.
First, you should refer to Allyn Miner's book for a historical overview of different tunings for sitars of the past. Seven strings has not always been the norm. I have read of some of the current sitarjis using less than seven, Vilayat Khan comes to mind. I don't use the Pa (5th) string most of the time, 6th and 7th strings remained tuned to Sa. I suppose that if you are playing in the classical style, you will want to adhere to the accepted tuning, but there are many variations out there and I should think that in history, experimentation with the amount of strings and their tunings is what lead to the sitar as we know it today.
Yes, from what I've read over the years, essentially every one of the "big names" of the latter 20th century had their own preferred tuning, as modified from the "standard". Plus the music itself has undergoing quite a bit of stylistic change. To keep from becoming confused, I just go with whatever my teacher recommends. That's another good reason to get a teacher, if possible of course.
Oh, I forgot to say that there is a new tuning that is slowly becoming popular with some players. It involves tuning the fourth string above middle sa in order to give a 3-note chord to the chikari. Fifth string left the same. Of course, you'll have to use a steel string for this, about the same gauge as the first. I've only heard about this second-hand, so I can't say what note its tuned to, but perhaps its up to the player?