I wouldn't study under a teacher based on mere ranking. See journeyman's post on belts/instructors here.
For me, the reason I know I'm with the right instructor is by actually experiencing his/her technique. For example, any black belt in the class may do a joint lock to me, and it's good; it's strong. But whenever my Sensei does the same lock I think to myself: "Oh yeah, that's why he's teaching... this kills..."
The black belt may have done wrist throw 100,000 times and be quite good at it. But Sensei has done it one million.
That said, I have often thought about different styles of martial arts and wondered which ones would complement my current one. But as I look at other styles I realize how much my level of interest in an art is due to the manner in which it is taught rather than solely what art it is. I've had classes in other styles but been reluctant to pursue them, not because of the art, but because of the teachers.
Likewise, I would be open to studying a style very different from my own if I felt that the instructor would translate it in a complementary way.
For now, though, I am happy. But my mind will remain open to good instruction wherever it is found.