I was worried about strength, UV, puncture resistance, color and transparency, in that order.
Apart from stays with family or friend, I camp most of the year. The vegetation down here can be very spiky. Current tent has patched holes from vegetation. Sometimes I camp in public areas, but mostly I'm in the bush. Current tent weighs 3.2kg, but I have another kilogram of cheap poly tarps because of leaks, punctures, bugs (yeah, some insect chewed holes), wear and tear that I can't seal enough, and sun damage. I also carry duct tape and sometimes silicone glue for repairs.
Current tent is silnylon that the maker rated at 6 months full time life in the sun. I try an avoid time in the sun with it, sometimes taking the tent down for the day, to put it back up on the same spot in the evening. Its a trade off. Sun damage or wear and tear taking down setting up. I was expecting cuben to last well since its used in sails, and they spend all their life in the sun.
Btw, I'm cycling with this setup, and want to lower the weight significantly.
Given the price difference between 0.51 and 1.43, I figured I'd take the risk on the heavier fabric. Most places, I'm a long way from anywhere to get a replacement shelter if it fails. Part of the reason I have the cheap poly tarps (>100gm/sq meter) in use now. They were all I could get at the time I needed them.
Even with using 1.43 I'm expecting to have a two person, tarp, no-see-um mesh sack, and bathtub at under 1.5kg. I'm hoping to get two years life out of it - more is better of course.
I'm using olive drab cuben. Cold is not usually a problem for me. I'm not likely to spend any time in the snow, mostly its heat that's a problem.
I was thinking to butt join the ridgeline, and then overlap a piece of cuben on the top and bottom, with tap and glue. Like this:
-- is cuben
++ is glue
== is tape.
The edges - one thought was to fold over the edge and glue with Aquaseal. Another was to fold and tape. Will see how sample tests work out. Tie-out locations will be reinforced glue or tape. I'll be using cuben strips for the loops.
I read the threat on strength testing using tape, Hysol and Aquaseal. It seemed that they were all pretty similar, with Hysol the best, but that tempered by being harder to use. Guess I'm trying to hedge my bets using glue and tape on the ridge line as I think a failure there will be more of a problem. Tape appeals as its quick. Aquaseal is easy to find as its used for diving suit repair. I'm hesitant about using the Hysol as its hard to get, and the short setup time worries me.
I really liked Zpacks Hexamid tent - but want to make my own gear. Tape and/or glue is important as I don't have access to a sewing machine and stitching by hand isn't going to happen.
I'm also hoping to use the 1.43 for a set of bicycle panniers.