Hi there. Stuart told me you were looking for this information, and since I have both of these shelters in cuben (with the new reinforced areas already mentioned, I'll pass on what I know.
The following weights INCLUDE guylines and supplied stuff sack:
Cuben Duomid 17.2 oz
Cuben Solomid 12.9 oz
The difference is 4.3 oz
This does NOT include stakes, because we don't all carry the same kinds. Nor does it include any pole extenders.
For a weight penalty of only 4.3 oz, the Duomid does feel substantially larger. There's considerably more headroom and width. I love them both!! If you place a higher value on having a smaller footprint (like me), the Solomid is sweet. I suspect most people will opt for the larger Duomid though, and for good reason. And as is mentioned in other posts on BPL, the Duomid (IF used for a single camper) allows you to have your sleeping gear in the back away from the door, which provides more rain protection when the door is opened. The Duomid is so large in fact, that at 5'9", I can lay completely flat and in a perpendicular angle (feet pointed at the door) as seen in the photo and can zip the door shut. I've waited out short periods of rain like this and had the upper half of my body on my sleeping pad and pillow.
The Solomid, on the other hand, has the sleeping area right square in the center rather than behind the pole in only half of the shelter. You can see that it appears substantially more narrow in the pic below. BOTH of these shelter totally rock!!!!! I'll probably mostly use the Solomid in the Sierras, but nobody will be able to pry the Duomid out of my hands any time soon! Hope some of this helps. :)