Gore-Tex
The Gore branded version was taken off the market as tent material because of fire regulations.
However Todd-Tex (a word play on Gore-tex by Todd Bibler) and Tegral Tex use the same principle of all PTFE laminates, that is ,stretched Teflon coated with fabric on top and some protective layer underneath.
Anecdotally (some tests by BPL confirm this) the most "breathable" of them all is eVent available (under another name...) with the Rab "bivi" series

http://www.rab.uk.com/equipment/bivvis/new_summit_mountain_bivi---140/
note that the max height given on the web site for the Summit Extreme and Summit Superlight is the top of the door not the apex.
(to avoid litigation the official max allowed height with eVent is 70 cm)
Starting from 12 lbs is not going to be difficult to get a lighter tent.
If your 4 season includes extreme weather , IE over 2' of snow and or 50mph plus winds, the above mentioned Hilleberg or ID/Bibler could do the job, but I disagree that you will find an ID or Bibler comfortable in hot muggy weather.
If on the other hand your winters are not that extreme and are after a versatile shelter than the Scarp 2 could be a good choice.
Keep in mind that the 2 pole crossover design (Bibler/ID/RAB) is specifically made for climbers where weight, small footprint and strength are priorities over livability, IE no vestibule . Yes you can add one to some of them but they tend to be heavy and cumbersome compared with the built in variety.
Franco