I flipped the coupler upside down so the neck keeps the bag "poofed" out during the boil. I think it does have a little impact on hoppiness, though with small-batch brewing the answer is... throw in more hops.
http://www.flickr.com/photos/kgs/sets/72157630594736916/ (That's not me about to fire up my burner on the office carpet... it's just where I stored my burner and kettle until I got a nice big shelving unit.)
I may try flipping the coupler over next batch. Though the bag already 'poofs' out quite large in the section that in the wort. I haven't really noticed any impact on hop utilization using the bag versus just throwing in, and it makes for a much cleaner transfer and fermentation.