Recommendations for lightweight 2-person tent?

Sub 2 lbs and a reasonably sized 2 person double wall tent are two things that are very hard to find in the same shelter. The HMG Echo II is not going to have the additional headroom you desire. The highest point in the inner net tent is immediately at the door and it just gets lower from there. Did you read the BPL review on the Echo II? I believe headroom was the primary weak point. I own an Echo I and headroom is definitely not its strong suit. I really like the shelter, but more headroom would be appreciated.

The SMD Haven is likely quite a bit better in this regard than the Echo II. They claim 45" of headroom and the highest point is right where you'd want it. It's also the same height from wall to wall (not just high in the center) so both people could sit up at the same time.

Maybe Alpinlite Terraform: http://www.alpinlitegear.com/index.php?main_page=product_info&cPath=4&products_id=51

and Bug Shelter 2.0: http://www.alpinlitegear.com/index.php?main_page=product_info&cPath=12&products_id=50

Looks like the combo is just over 2 lbs though.

The Echo II's inner net does sag a bit, so it's definitely lower than the tarp. I think you can tighten it up a bit to regain some of the headroom lost to sag, but there's a limit to how much you'll get with that approach.

It's enough headroom for me, at 5'10 — at the front. I'd be able to cook in it, especially if I made sure to set the front pole to the recommended 48" length.

But like all tapered, cat-cut tarps, the headroom drops off as you move into the shelter.

Another option might be to get a square tarp with cat-cut sides like Lawson's over at Mountainfitter, and talk to the folks at Bearpaw to set yourself up with an inner tent that meets your needs.

http://www.lightheartgear.com/LightHeart_Gear/Duo_Specs.html

sub 2lbs with net in cuben fiber. not cheap

net dimensions:
Long = 90"
Wide = 50"
Tall = 46"

tarp is bigger…

Tarptent Squall 2 or the Gossamer Gear Squall Classic would be my recommendations. If you must have the double wall, check out the Easton Kilo as it has a bigger vestibule, higher PU, and carbon poles.

Sorry, I cant contribute more, but I would like to toss in my 2cents about the duomid. I would recommend against the duomid for 2 person use, if you plan on using the duo-inner. We found the steep sloping sides to encroach too much on the living space to make it a comfortable two person shelter. We use the double rainbow for 3 Season, and shoulder season here in the NE, but unfortunately it's 2 1/2 lbs and not double walled as per your requests. As another poster mentioned, if you're okay with single skin, than the squall 2 almost fits the bill (2 ounces more than 2lbs, but 2 inches shorter than your desired length.

It's going to be tough finding a 2lb shelter that actually comfortably fits 2 full size adults (and their sleeping pads for that matter). Most 2lb shelters are more like 1.5 man tents, (aka palaces for 1). But as mentioned, if you're okay with 1/2lb more, take a look at the TT DR or the SMD Lunar Duo

Edit* Actually, I think Anna nailed it. I totally forgot about the LightHeart Duo. If you carry trekking poles, It's a solid bet. Not quite double wall, but pretty darn close (it's a similiar hybrid silnylon design seen in the TT DR, so you have 2 large silnylon panels that may collect condensation). Based on what I've read, I would go with this before the TT DR or the SMD Lunar Duo

Though it does not quite fit your specs, you might want to try the Easton Kilo thread. The Kilo is very close to 2 lbs.

You might want to check out the Lightheart Duo – 42" of headroom, plenty long and two doors. Two lbs in silnylon (w/o stakes or seam sealing) and much lighter in Cuben.

http://lightheartgear.com/LightHeart_Gear/Duo.html

This is an interesting tent, but would it be improved with a vent at the top of the fly?

Hexamid Duo is another option.