"Will the mld duomid be big and cozy enough for 2 adults"
Short answer...no. The duomid, although designed for two, is no palace for more then one person. Don't get me wrong, this shelter rocks, but it is not a 2 person shelter that will be big and cozy. As far as I know, I received the first duomid in Cuben off the line and I absolutely love it, but if I were to use it as a 2 person shelter, it would be for light weight, fast pursuits and not for a big and cozy setup.
One issue when sleeping with 2 is that there is no vestibule. This will allow rain/snow to fall on the sleeping zone of one member. Also, when I use it solo, I angle the pole towards the entrance in order to give myself some additional room - which is not possible with 2.
In short, this shelter is great (I love it), but your question was if this will be big and cozy for 2 adults - and it will not perform this function. Go with the bigger mid.
Hope that helps.