29QBS was 29QBH, could be as simple as they making a model # change.
But I do question you saying it "such a popular model". I have one, and we love it, but I have never seen another on the road or in the campground. I see tons of 32BHDS and lots of 28BHBE; so my guess is it's really not that popular of a model.
We bought our because it was ~32' and not ~35' of the BHDS which made a difference for where we camp. Now that the QBS has creeped to ~34' I guess it's a much smaller step for the dual slide bunk house.
2007 Chevy Duramax LMM/Allison
2012 Jay Flight 29QBH
2012 Jay Flight 26BH (Sold)