The WildThings epic pullover, for me, is more wind and weather resistant providing better protection in very cold winter weather. The Houdini being lighter and airier works better for three season use. I own both and this allows me to select the wind shell that I prefer for expected trip conditions and seasons.
The epic windshell allows me to endure bad winter weather conditions longer before having to pull out the Arcteryx LT. If I could only have one windshell I would likely select the Houdini and just resort to pulling out the hardshell sooner.
Others may have an opinion different then my own but this works for me.