I am considering trying a quilt. I keep reading that quilts are warmer because all of the loft is on top of you. What if I used my WM Summerlite like a quilt? Would tht lower the temp rating? It would put more loft on top just like a quilt. I know the sleeping pad makes a big difference. But lets neglect that for now. What do you think? Does anybody know someone who makes affordable quilts to try out, or just to take on trips when I may be couch surfing?

The quilt is warmer if all the weight of the down is on top. If you just unzip your sleeping bag, you'd have to be able to shake the down that is in the parts of the bag that are now lying on the ground to the center so that down is over you. If you can, then theoretically, it would be warmer. In practice, it's only warmer if you don't move around when you sleep and cause drafts. Also, a quilt is warmer when you tighten the straps so it hugs you. You can tuck the edges of the sleeping bag (or quilt without straps) under you to get the same effect, but you need to re-tuck when you move around in your sleep...

RayWay.com sells some inexpensive quilt kits.

It would be very hard to keep the loft all on the top of the WM bag through the night, plus the WM bag is wider than most quilts, so will only give you a general idea of how quilts work. The WM bag also has a sewn in footbox, which many of the cheap quilts do not, and a hood and zipper. If you use all of these features together, it will be warmer than a quilt of similar loft. By all means, try the bag unzipped as a quilt to see if you like the freedom of 'quilting', but keep in mind these differences before splurging on a quilt. One way many people minimise these differences is to use their quilts in conjunction with a bivy bag, which works well, but negates any weight savings, and I find bivy bags a pain to get in and out of. YMMV.

unless you can move all the down to the top it wont be warmer

the other issue is the dead air space ... unless you can get rid of that, it wont be warmer

i personally find that opening up a full zip bag as a quilt worsens the comfort temp byt roughly 10F+ ... which just adds to the flexilbility

Both my wife and I do this a lot - me all the time these days. In fact, I have removed the 3/4 length zip to reduce weight.

One advantage is that an opened SB is wider than the typical quilt, so it blocks drafts much better. Another advantage is that when sleeping with my wife I can always throw my quilt partly over her as well to keep both of us warmer on cold nights.

Does it lower the temperature rating? Uncertain, but probably by a degree or two. You see, since the fabric is no longer tight around your body, the down has a chance to fluff up a bit more. The loss of a layer of compressed down under you has no significant effect.

You will need to pat the down around a bit to get it into the middle, but that is easy to do before you go to sleep.

Cheers