Beg to disagree with Dan's positive comments about the tents. "REI's doing some good stuff."
The QD1 looks like someone started with the old Eureka Crescent design and jettisoned a pole to save weight; thus losing most of the stability of the Eureka, not to mention the freestanding feature.
The Dash is not just a matter of the fly not coming all the way to the ground. One may want to do that at a vestibule on one side of the tent just to allow some air to enter for low venting. Rather, it extends the coated WP floor up the insides of the tent, at head and foot ends no less, and eliminates fly coverage at these locations, thus making the tent partially single wall.
Sierra Designs tried the same trick with the Bike Light, and more recently, Nemo did the same with Obis. What you get is condensation at the worst possible locations, where your head and feet rub against the unprotected tent walls. It is surprising that a company with REI's experience would do this yet again.
The TarpTent tents that were raised as comparisons have some issues, but nothing of the magnitude of what REI has done here. Strange.
Submit that a couple features are a must if a single wall is to have any versatility:
> Head, foot and sides must be protected, at least closer to the ground, by some kind of barrier, usually inner netting.
> The canopy material must not absorb water, like most coated nylons. Rather, a film-coated matrix like Cuben, or polyester, or specially treated nylon must be used.
Otherwise, the occupant will be perpetually subjected to wet inside walls above the protective netting. 'Oh I just have to occasionally swab the inside walls,' some say. More likely we swab them with our heads when we get up in the night. And swabbing won't help much once the nylon has wetted out, as it is prone to do. Are a couple ounces of weight reduction with a single wall worth it, when fairly durable netting is readily available at 0.8 oz/sq/yd to protect against the wet walls?
Nonetheless, I decided to build a tent with single walls at head and foot ends from about a foot height up. It will either be Cuben, or nylon specially treated to resist moisture absorption. Could not find an ultra light (sub one ounce) polyester that wasn't as stiff as sail cloth. What deterred me was not so much the condensation issue, what with the fair amount of protective netting, but that the lack of elasticity in the materials would make the canopy more likely to tear apart in high winds. Will give it a go, anyway. But the point is that these are the kinds of issues that manufacturers should be addressing. Instead they are making worse tents.