Hi Cookie. To get the lightest and smallest packed size, a quilt would have to beat a sleeping bag, loft for loft, because there's less fabric and less down. Some places do detailed custom sizes.
Some people can't adjust to using them. I'm a cold sleeper, side sleeper and tosser-and-turner (about 10 cm shorter than you and 8 ish kg lighter). I went for a regular width and length quilt, because of those issues, and because I like to be able to cocoon myself inside, using the top part of the quilt as a hood. Other people use a beanie or balaclava and get a shorter quilt, using the drawstring to cinch it in around the neck like it's designed to be used. In case you haven't seen these quilts, most if not all have straps that go around your mat, that you can cinch in around you when it's cold. Some have a small zip to open or close the foot box (which I highly recommend), and I think most quilts have press studs to bring the quilt in around your legs. You can toss and turn mainly underneath the quilt, instead of taking it with you like I do with a bag.
You mentioned you have an Exped mat, but there are a lot of different models. Do you know the R value of yours? I reckon a quilt relies a bit more on the quality of your mat, though down squashed underneath you doesn't do much for warmth. There are some types of mat that don't work with a quilt - ones that have little depressions for a sleeping bag to 'loft' into underneath you.
I do like my quilt. It's not much more than half the weight of my old bag, just as warm, and packs much smaller.