It depends on what you mean by quilt. There are some that are just insulated sheets. There are also some that are hammock top quilts. Then there are ground-sleeping backpacking quiilts.
On the ground, you lose heat into the ground through conduction rather than radiation. You can lose heat into the air through convection, and in all directions through radiation.
Fluff insulation like a down or synthetic fluff held in place with a polyester or nylon cover (a sleeping bag or quilt) will be especially effective to reduce convective loss and radiated loss in the directions where it can fluff. It won't be so effective when it's squished under your weight. That's why we use foam or inflated sleeping pads.
The backpackers quilt comes about from the desire to shave weight -- the weight of mostly ineffective down or synthetic insulation fluff on the underside of the bag that often just gets squished by your weight. Such a backpacking type quilt should have a pocket or some attachment system so it fixes to the sleeping pad. It's an ultralight thing.
As a weight-concious backpacker of almost 40 years experience, I think the quilt/pad system is smart -- smarter than a traditional bag and pad. However:
It doesn't make any difference if you're not packing it on your back. It's superfluous for camping out of a vehicle.
There are other alternatives like the hammock, though they're applicable in fewer circumstances.
The options on the market right now are mostly high-performance down paired with inflatable pads
people seeking the advantage of the lower weight of quilt/pad systems are unlikely to forgo the advantage of high power down and inflatable pads
down and high power down are $$$
down performs poorly when wet (which is inevitable after multiple nights just from condensation)
ultralight shells tend to be delicate and they typically pair with inflated pads (lower weight than closed cell foam) that are also delicate.
The combination of expensive and delicate cancel the benefits of ultralight highest-R value per ounce quilt/pad systems for me. I sleep with a 90 pound dog when I'm backpacking, so I go inexpensive synthetic and it's a traditional bag and closed cell foam pad. They're more durable and less costly to replace. It might weigh a full pound more for a given warmth rating. I'm happy with the tradeoff but others will opt to spend the money and save the weight.
Last edited by Western_Juniper; 07/17/21.
