I've worked with both the CTB1B3-1.0 and the CTB1B3-1.0/NF.
There's a bivy collabo between myself and TiGoat in the works using the NF. ;) It weighs essentially the same as 20D Intrepid/Momentum, and does appear to be very breathable. The durability for this type of use seems completely adequate from what I've seen so far, but that doesn't include any significant field testing yet.
One disadvantage of the CTB1B3-1.0 is that it can't be bonded, period. It could be dielectrically welded or laser welded, but I don't think it would be very strong. However since the spectra is ptfe coated on both sides, it seems to be more resistant to tearing than the mylar faced stuff.
One quirk of both fabrics though, is very high bias stretch. I'd be really interested to see some in an HB configuration with a very light spectra core, but I'd be very afraid to see the price tag!
Another awesome thing about the NF stuff is that the color shows well on the non-ptfe side.
And yes, it's definitely waterproof. I'm kind of confused by the MVTR/HH numbers I've seen, but I"m guessing it's just because they're realistic instead of hypothetical test-magic that the normal WPB manufacturers comes up with.