I received the RAB Quantum 800. It is indeed longer, it would be a long by US standards.
I'm 5'10 and can fit in the bag entirely, no need for a hood :). Shoulder girth is only 55", quite narrow, even for me at 140 lbs, but I was able to fit with a fleece on; I have regular width shoulders, but I am slim btw. Since it's so narrow in the shoulders I feel the lower half of the bag should be narrower. This bag is best for a tall guy with narrow shoulders and big long legs :).
The pertex on the outside is more solid than whatever they're using on the WM Ultralite or MH Phantom 32. The zipper is 4/5 length and opens both ways.
It has a differential cut, is rated for -18C comfort, and it has enough 850 fill down for me to believe the rating is accurate. The loft is a minimum of 7 inches. The baffles are continuous as far as I can tell. The bag weighs 1410g.
I can't decide if having a longer winter bag is good or bad, but it was definitely a good deal.