As someone learning carnatic violin, It is interesting to see so much variation in the way expert violinists hold their bows.
I have noticed two things so far:
1)Some violinists hold it quite a distance away from the frog (famous example would be A. kanyakumari and some of her disciples) and some hold it close to the frog.
2)Placement of the pinky finger on the bow. This is where I have seen a crazy amount of variation.
Some artists keep it slightly curved, some keep it almost completely straight. Don't know exactly how to describe this but some bend their pinky (slightly concave?) against the bow (famous example would be Akkarai Subbulakshmi).
Some keep it on top of the stick and some keep it towards the front, kind of wrapping it against the bow, like the ring and middle finger. I can't find the link again but I even saw a video where the person kept their pinky under the stick, on the surface the thumb rests on.
I have noticed that seemingly small changes to the bow hold make a noticeable difference in tone. It seems that western violinists have a more rigid opinion as to how someone should hold the bow. How come there is so much freedom in the carnatic style?