I use a french bow. I had been instructed by my teacher to hold the bow with my thumb below the metal; on the very bottom of the bow. This seems very comfortable and natural. Then I go to an audition for college, and the bass instructor there said something to the effect of "get a new teacher", and that you must hold the bow between the two parts that split. Now, I like my teacher, and I like the bow hold he told me to use better. What's your opinion on this issue? Is it an issue of preference?