After reading the review on this site, bought the spiral down hugger #3.
It remains perfectly filled with just enough down to fill out all areas of the bag.
Then came the reviews, posts and articles about the 'super' spiral line, and thought I had really missed the boat.
Since then, however, there have been a number of posts suggesting, like yours, that the supers don't completely fill out. Not sure what is going on here. There was an article here that compared, or at least had data on both the regulars and supers; but it did not fully resolve the issue.
At any rate, am happy with the not so super bag, never compress it except when carried in the pack in a large stuff sack with no compression straps, and when it gets rank, will launder it with Sportwash on the sweater cycle, and dry very slowly in the dryer with tennis balls. So far so good - much more warmth for weight than the synthetics used previously. With BPL cocoon PG top and bottoms, plus Thinsulate booties over sox, and BD fleece top and hat, it is comfy down to a few degrees below freezing; mid to high twenties, in other words.