Totally foreign area to me as I've only ever used a sleeping bag.

What are the differences/advantages/preferences?

Think of a mummy bag, then think of your comfy bed at home. That's the difference for me. I find the quilt lighter, more versatile and sleep much better in them.

Keep talking, if you don't mind.

All I've tried are Enlightened Equipment quilts. I run regular length and wide. I'm Joe average, 5'10" 190. I've had four and still have two of them, just sold the others to dial in my gear. Generally speaking I'm a terrible sleeper so I will do about whatever it takes for a good nights sleep. I've had folks say they are bad in cold but I had no issues down to single digits. I knew it was going to be cold so wore my standard skull cap and also a fleece hood that goes down around the shoulders. I didn't feel like it was a minus to my gear as it was also worn during the day due to the bitter cold. I now have a synthetic quilt, 30 degree, that will unzip to lay completely flat. Also have a 10 degree down with sewn footbox. Both quilts together cost about what one WM bag will run you. Any specific questions?

Last year I switched from a 20deg mummy to the Enlightened Equipment revelation 10deg and I ain't goin back.

Coupled with an Exped downmat 7 UL, it is the most comfortable backcountry sleep I have had.

On 50 degree nights unzip it flat and kick both feet out. On 15 degree nights you zip up the footbox and wear a beanie and some midweights to bed.

Much colder and I would pay closer attention to the stove and wood supply.

Very interesting. Lighter, more compact, and seemingly more comfortable. What are the downsides?

I haven't found any yet.

If you do primarily winter camping, a mummy with draft tube and hood is probably a better mousetrap.

I used my quilt over 15 nights this year, best year in quite some time.

If you are a strict back sleeper a mummy might have advantages. I'm mostly a side sleeper who tosses and turns, I've seen no disadvantages yet to a quilt.

The Sierra Designs Backcountry Quilt has an interesting and very effective "Hood"
I have well over 30 nights in my SD and I prefer it and my Neo Air Xtherm to my regular bed at home. The SD is only good to around 30 F without supplementing it.
It isn't the lightest but is my favorite of the 3 or 4 quilts I have tried.
I think like Brad stated, with a quilt go with a wide width or else you will get drafts unless you sleep like a mummy.

http://www.sierradesigns.com/product/backcountry-quilt-800-2-season

I have been traditionalist with the mummy for over 40 years and am about to give up camping/backpacking as a monthly pursuit. If I did extend the trip I would surely consider my neo with a wide quilt as I am a side/belly sleeper now and like to spread out unlike during those younger, high seratonin days of yore.

I used a Golite quilt for a summer of backpacking while working for the USFS. I hated it. I found it shifted obnoxiously unless I spent more time than I care to fiddling with it to get it perfect. I also don't like the draftiness. You can combat this with a wider quilt, but you're starting to gain back some of the weight you saved there. In most conditions they aren't mathematically as efficient of an insulation strategy, based solely on physics.

I played with a bunch of temp. equilibrium equations in a graduate level ecophysiology project a few years ago. It was hard to make a quilt pencil out once the temperature crept below freezing.

The guys who like them are correct with all of the "pros" they list too, just not my cup of tea. They can be a great tool if you appreciate their benefits (which are real) more than the downsides. For fastpacking in moderate weather I'd still consider using one, despite them not being my favorite.

My go-lite quilt is my go-to for night time temperatures of 20 degrees F and warmer. I spent 6 nights in Montana with temperatures between 15 and 25 degrees in a one man tent and was comfortably warm with a base layer and stocking hat on. I am sure the quality of the down makes a difference. With a tapered pad it is a much roomier and comfortable sleeping system than a mummy or tapered bag for me.

Quilts are not for me. I tried it and went back to a sleeping bag.

I don't, however, use a mummy bag. Way too confining. I have 3 Western Mountaineering semi-rectangular bags.

The closest comparison is between my quilt which was rated at 35 and my WM 40 degree bag. Weight is pretty close but I can't stand sleeping directly on the NeoAir pad so with the quilt I have to add a sheet. That's 100% weight gain, no offset. Further, I don't like the quilt on the 20" wide pad but the sleeping bag is fine so I'd really need to go up to a 26" wide pad and add that weight, too, to improve the quilt situation.

I still use my quilt but only car camping now and only with a 30" wide Cabela's cot pad and a real full sized bed sheet. I'm pretty fond of it for that use.

Tom

I love my quilt but if I knew it was going to be <10� I would probably take a traditional bag with some type of hood. I toss and turn a lot and sleep on my side so the quilt is way more comfortable than the bags I have owned in the past.

I use a combination of bag and quilt Mountain Laurel Design quilt w/Event fabric , WM Mitylite semi rectangular bag , between those and a down jacket and vest -beenie I can do fine.
I'd say a Quilt is just a good piece to have -you probably would have to buy or borrow one to see if it works for you.

My WM Mitylite can be used as a quilt though.

Only used a Jacks R' Better quilt on the ground for 18-20 or so nights, few below freezing. To push a quilt lower than that wear a down vest that you've sewn Omni-tape to the collar and attatch a JRB Down Hood to the vest. The Jacks say that will lower their quilts ratings 12-15 degrees, and they are old guys.

Another tip from the Jacks (JRB) for ground dwellers is to contact cement a strip of omni-tape to the bottom edge of your ensolite pad. Sew another piece to the edge of your quilt. This is best for side sleepers and done on the side your back faces. This keeps you from having the winter wind blowing up the crack of your azz. You can tuck the other side in with your arm. The "hand pocket" that Sierra Designs includes might be a good idea.