I don't know how tall you are, but the 15.5 and 17.5 X-caliber WSD are IDENTICAL to the men's/unisex X-caliber (check out the specs on the trek website). Except for the color. Maybe the 14.5 in frame is designed differently?

Anyway, if you are someone who usually needs WSD because of proportions, I would make sure you got a really good trial ride on that one before commiting. I think it's a wonderful bike, and I almost got one, but I can't ride most WSD bikes.