>Maybe the Trailstar is stormproof on a perfectly flat dirt driveway elevated above the floodplain with good drainage. I don't doubt it, actually. In real life, though, my campsite could be at a 20º angle, or it could be rocky and uneven, or it could be in a bit of a puddle. You never know. The bivy is supposed to act like a backup to the tarp for spindrift, wet ground, and the worst-case scenario of a torn tarp.
Max, FWIW, the Trailstar is very versatile with its pitching options. It's also one of the most storm-worthy shelters on the market, besides the big beefy tents. Uneven, rocky, and brush-filled terrain, to an extent, are workable with the Trailstar.
It's main drawback is its large footprint, so if you found yourself in locations where there really was no real estate to set down on, you'd have a little issue.
But a more storm-worthy and adaptable tarp you won't find.