For $75 more you give up 14oz (almost a complete pound) and you can sit up and move around. Snugpak uses a heavier material so it is to be expected.
The Trekker weighs and costs the same as the Stratosphere but even with the same weight you can sit up. Open both wings.
While I almost bought a Stratosphere today I have to acknowledge that cost and weight is a big deal and a meaningless purchase. The Stratosphere weighs 3.5 pounds where a Bora bivy and tarp weighs under a pound and that's if you're interested in weight. There are less pricey tent options that weigh less and give you more room. So just forget it. The only way this becomes a good idea is if the price or weight drops by half.