I've experienced strong winds with the Lunar Duo in southern Utah, and agree that it has a bend but don't break style in those conditions (in a good way). One can get pretty creative with the various additional tie out options. I've had good luck running a line from the loop in the center of each side, up to a trekking pole or stick, and then down to the ground. You can even thread the adjustable guyline at each vestibule through the upper vent, allowing much greater range of variation in its angle, and even the ability to tie it directly to a tree, rock, etc. In those cases the bottom of the vestibule could either still be clipped as designed, or staked directly to the ground. A bit of extra line gives you many options.
As you said, not a four season tent and doesn't claim to be. Most of the time, you don't have to bother with any of these extras, but it is nice to have them when conditions warrant. Now if they could only invent a mesh that selectively blocked blowing sand...