I'm only replying because no one else has so far; hopefully people with better experience will chime in. I have only beginner answers:
I think the practice is a matter of existing on a spectrum and perhaps bouncing back and forth between the "opposites" to better enagage them into a cohesive whole (better mind-body interactions). When I've been playing around with it I've been focusing on feeling the expansion pressure inhaling causes when I don't allow my abdomen to inflate. I think of it as breathing through the back (mostly) and I usually feel it just above my hips/below my kidneys and traveling up my back along the rear "corners."
I'd like to add I actually try to feel down into my hips when I'm doing this...not sure how right or wrong that is though.