Quite a bit of difference in bulk between a bag and a quilt (I like small narrow packs), and weight as well, though that wasn't as much an issue to me. Try as I did (2 different quilts), I ended up with a heavier bag than is likely more than necessary (WM Ultralite), and I'm satisfied.
Very warm and comfortable, no fuss, and I have one bag for the camping that I do.
If you have the time, try to keep an eye out on the forums for one of the original Golite Ultra 20 quilts and give that a shot, if you don't like it sell it back for little/no loss. Part of me wishes I kept it for the warmer trips. The width was nice, though wider would have even been better as a side sleeper. Then you get into the bag weight territory of course.
WM and Montbell get mentioned a lot on this forum, as well as the others mentioned above. The Kelty is not a bad bet for $90. Good to have a back up, loaner, car camping bag. Who knows, maybe you'll be happy with it and save $200. I'd try a Montbell Super Spiral on sale if I was you.
Whatever you buy, if you pick one of the bags that get mentioned often in these threads you'll, from my experience, get your money back if you re-sold; especially so if you got it on a good sale.
With the quilts, I took a hit because quilts by cottage industry manufacturers are full retail and you'll eat that if you don't like it/need the money.
Good luck. Most costly part of my kit when all was said and done (2 quilts, 3 bags tried).