What pad do you use with your quilt? Also, do you take any special precautions when using a quilt in sub-freezing temperatures? I am intrigued by the idea of using a quilt, but believed, perhaps erroneously, that they were ill suited to sub-freezing temperatures. I am interested to know more about your experience with the quilt in cold temperatures.
I just got my Enlightened Equipment Revelation 10F in long/wide today. I got the 800FP treated down with some heavier 20D material for the foot and around the top. This thing is super nice. Very good build quality and super versatile for a wide range of temps. Fully snapped/zipped it's basically a hoodless mummy bag. Weight with a 10L OR dry sack is 29 oz. I have it paired with Neoair Xlite in long/wide, Jimmy Tarp Granite Mountain w/vestibule and a polycryo ground sheet (shrink window film). My whole system with stuff sacks etc weighs in at 3 lbs 13 oz. I'm new to the quilt thing but given how much I move around when I sleep I think it will be a good switch. I'll give it a real test next weekend on my annual traverse of the Bob Marshall Wilderness.
For spacious light weight bags in my price range I would look at Big Agnes or Marmot. They both tend to make more spacious lightweight bags than competitors without getting super expensive to save a few ounces. If you're able to spend more money to cut ounces, and get even more spacious, look at NEMO brand.
My go-to bag is so old I can't read the tag. I'm pretty sure it was a Marmot in the 40 degree range, and I'm pretty sure they don't make it any more. A few years ago I had the fortune of getting stuck in way colder temps than I expected. I could have bailed out and never found my first 4x4 muley the next morning, but I dug out the space blanket that I'd hauled around for years and stuck it out. I used that bag, a foam pad, and a space blanket over the top on an October night that got to -12 and only I only felt cold when I poked my head out. Ever since that experience I use space blankets all the time. They are such a cheap and light weight way to add warmth to your situation.
My coldest backpacking bag is a Klymit KSB 20. It does taper down, but the stretch design makes it feel roomier than a typical mummy. I can't stand regular mummy bags, but this one is tolerable. I haven't been in anything nasty with it, but its warm enough in a snow cave without a space blanket.