Maybe you've noted some of the lengthy threads in the last year or so about this issue, not to mention the other big issue, water resistance, especially after considerable use in the field.
Thanks to Richard, the water issue was addressed to a large extent. Some may not like the results, but they are a lot more definitive than I ever thought we'd get. The type of cuben appears to be a key factor.
The durability issue is tougher, and I haven't been able to reach any firm conclusions. There seem to be nagging questions about what happens at the needle holes if there is stitching, and about stitching causing the non-elastic material to pucker. While a fly or a tarp can be bonded and taped, what about a hybrid tent, where cuben material and netting all come together at one 'seam' location? Since hybrid designs are my passion, this has been a thorny issue that I'm still giving much thought. I'm so conditioned to thinking in terms of conventional sewn fabric construction, that it's taking a lot of time. One approach has been to think of cuben as if it were metal foil, and try to envisage how pieces of it could be joined into an arced tent structure that is taut.
You can't get around the fact that in a tent, it's the fabric that is most key to the total weight, especially if the poles are carbon or dual duty trekking ones; and since cuben weighs about half as much as silnylon, there is a strong incentive to make it work to achieve a much lighter tent.
There are several manufacturers making cuben tents (Terra Nova and Lightheart Gear, to name just two), and it would be nice if BPL would test them as a group, with info about durability, and construction.
In the meantime, those who can afford it may just have to make or purchase cuben tents, and we will eventually find out how durable they are. I'm planning to make one this winter, but won't have any good idea of how durable it is until late next year, after some hard use; so it's going to take some time. And not too many are inclined to be very critical of something they put a lot of time and/or money into, and that is a factor also.
Once I settle on an approach to joining the shell, floor and netting materials together into a tent, I'm going to just bite the bullet and build an all Cuben one, and find out if I can do it without puckering and/or separation at needle holes. If it doesn't work, I'll be poorer and still carrying a heavier tent. If it does, it will be much lighter than the silnylon designs I've been working on, and therefore worth the $ and effort. Go for it!