I would stick with the 1.1 double at your weight. I've used other hammocks made from a single layer of 1.1 fabric and definitely noticed the stretch at around 200 pounds.
For a Blackbird, in my opinion the quilt question is a no-brainer - Yeti all the way. The fit is pretty close to idiot proof, and it is toasty warm. I have used pads, DIY quilts, other 3/4 quilts, and the Yeti was the most foolproof and easily managed of all of them. I LOVE that quilt. Don't think of it as skimping at all. A full length quilt is harder to get a good fit on, because the suspension naturally wants to pull it straight, and you aren't laying straight. With a pad under your legs, the quilt fits your torso area perfectly, and you are free to move the pad around as you see fit. It's the best of both world.
Cold sleeper, you say? I took a Winter Yeti + leg pad to 11F at the Colorado Fall Hang, the first time I'd used it.