In the inaugural issue of Headwall, we reviewed a handful of ultralight shelters. I've found a tent we didn't include that works great for me and doesn't even weigh three pounds in fast fly mode: The Big Agnes Copper Spur UL 2.
The Copper Spur's six inches longer than the Seedhouse we reviewed, and consequently it weighs a couple of ounces more, but the extra length is critical for taller folks and should help keep the foot of your sleeping bag dry. At 5 ft. 11 inches, I find the 84-inch Seedhouse too short.
In fast fly mode (set up sans tent with footprint, poles and fly only), the Copper Spur provides adequate shelter for two full grown men in mild weather. It won't keep you perfectly dry in anything more than a light shower, but you'd get enough protection from all but the fiercest storm to survive an unpleasant night. If you're expecting a blow, carrying the tent adds only 14 ounces to your load.
Expect to pay $400, about $80 more than the comparable Seedhouse. But if you're even average height and want to backpack with a buddy, it might be $80 well spent.