I use a 40* Apex throw from VI AM. Basically a slightly simpler, lighter woobie. I typically take it on late fall/early spring trips when the temp bounces back and forth above freezing, and short day trips when I don't have a quilt with me.
The woobie is advantageous vs just using the quilt for a couple reasons. First, getting a down quilt wet is a bad deal. If it's not well below freezing and there's snow on the ground or precipitation, there's a chance of getting the quilt wet. I've left the throw/woobie home on very frigid hunts (under 25* the whole time) and just used my quilt while glassing to save weight. No danger of it getting wet when it's that cold out. Second, the woobie is more durable material than most down quilts. No worries about snagging it and losing all of the down from a baffle.
The woobie has a couple advantages over puffy pants as well. First, I think it traps heat better. Less of it gets compressed while sitting, and it covers more of the body (including feet). Second, it's quick to throw on and off. I can't imagine wanting to hike in puffy pants, I'd sweat like crazy. The throw takes no time to put on and stuff back in a pack. It's also multi-use. Woobies/throws are big enough to add another insulation layer to the entire body at night, and make a good pillow when it warms up a bit.
