With any quilt and with the Zpacks sleeping bag, you'll need a separate hood, which makes the weight comparable to that of a sleeping bag. Do note that the ZPacks bag, like quilts, is not EN13537 rated.

My sleeping bag is the Western Mountaineering Ultralite. While WM claims it's a 20*F bag, and (last I looked) doesn't list EN13537 ratings, they do sell their sleeping bags in Europe so do have those models tested. I checked several European websites and (after converting to degrees F) found that the "lower limit" is about 17*F and the "comfort" rating is abut 25*F. The latter temp is exactly where I need to put on extra insulation inside the bag, so for me it's accurate. I've taken the bag down to 15* F wearing all my insulating clothing inside and with an R 5.7 pad.

Even if a bag is accurately rated, note that the "comfort" rating runs from 7 to 9 degrees F higher than the "lower limit" rating (which is usually close to the advertised rating). Ignore the "lower limit" when looking for a sleeping bag! And if the bag isn't EN-rated, assume that for us cold sleepers, the advertised rating is 10* lower than what it will be for us!

Just out of curiosity, what were you wearing in bed the night you were cold with the EE quilt?

Also consider that for many of us, a good night's sleep is far more important than a few ounces of weight saving.