Your setup looks good, I did have a question concerning the back light, when i was in college, they had said to never place the back light directly behind the head, but to place to the side. This tends to create a slight shadow on the top edge of the head and create more depth in the subject, as well ans placing it slightly down to put the depth toward the top. Do you feel you are getting a better quality photo with your setup, or had you tried the off centered lower back light yet?
Dolanimus