Cost: A lot.
Tie-outs: Yes, there are tie-outs along the center of the long sides - I anticipate these will usually be used (which is why I didn't cat-cut the long sides) as the shelter is pretty broad along it's length and will need to be guyed out well in wind. I believe rigging peak tie-outs - to stretch the shelter along it's ridge line - will also help with pitching. And yes, the tie-outs are completely Cuben and mostly (there is one bar-tack) bonded. I want to protect my "trade secrets" so I don't want to go into too much detail about their design, but I will explain the purpose of the bar-tacks: I believe that bonding is a superior method for joining Cuben, but like anything, it can fail. The usual failure mode is for the Cuben to tear where it is not reinforced (the bonding is that strong), but it is also possible for a slow creep/slip of bonded surfaces (depending on the bonding agent used). The bar-tack is not structural (in fact, needle holes actually weaken Cuben) - the purpose is to prevent creep/slip (which it does quite well). The structural strength is in the bond itself. I use a wide stitch to minimize needle holes.
Remains to be seen: Whether condensation will be an issue or not.