tarp vs tent.
For me, it's more about the guylines and the netting.
I've never actually used a tarp, but when sleeping in the hexamid it certainly feels like what I'd imagine sleeping under a tarp would be like. The noseeum netting while keeping it enclosed like a tent subjectively "feels" like nothing is there and I'm on the ground. I quite like it. The cuben is pretty see through as well, in a good way.
I've never slept in a moment, but I have a TT Double Rainbow. Though it can get quite breezy, as opposed to my buddy's 9 lb double wall North Face (super comfy, like sleeping in my living room), the DB feels like a tent. The set-up, pole, staking it out, etc.
And under most windy conditions that "generally" will face 3 season campers, the hexamid is solid. I don't usually camp in hurricane force winds, but if I happen to be caught in such a situation, I'd be equally sketched out in either tents under discussion. Kind of a moot point.
I also survived this night quite comfortably. That's all night early season Pacific Northwest snow (heavy, but otherwise calm night):
And here's a recent photo of one with a decent pitch with the 1.3 oz pole and optional door folded down.. got pretty windy that night:
The cuben floor from Zpacks made the tent a keeper for me. Being fastidious and kind of a nancy about things, it was the clincher.
Also, I'm a huge Valesko cheerleader. Dude's a joy to deal with. I wish I could buy everything I need from the guy just because of his customer service. I always look over his offerings first when the gear itch hits me. I know from experience, once I own (not even necessarily buying directly from him) one of is products, I'll be taken care of.
Having said that, when I think of other tents, the moment is the first thing that comes to mind. I'm pretty happy with my decision to go with the Hexamid (solo) and Double Rainbow (solo luxury, plus one).