I was considering purchasing one for Chicago loop weather, but reviews on amazon indicate that if your wind is non-uniform (and in Chicago, it is), the umbrella fails as it constantly tries to turn into the wind (and they tend to be shoddily made). Oh well.
I can confirm that the Senz performs quite well in Chicago weather, even in the wind-tunnel areas.
The problem, though, is that fabric is removed from the front of the umbrella to create the wing shape, and the result is less coverage than an un-aerodynamic umbrella of the same handle-length. So your feet and pant-bottoms almost always get soaked in any situation where you would actually need an umbrella.
