What is the difference between the Schoeller fabrics WB-400, Dynamic and Dryskin? What other fabrics are they most comparable to? I have been unable to find a good description of them other than WB-400 is like PowerShield.

Did you try search? There is a thread on WB-400 vs Dryskin.

You will find these interesting:
http://www.psychovertical.com/?cuthecrap
http://www.verber.com/mark/outdoors/gear/clothing.html#SoftShell

Think of dynamic as a heavy duty version of the nylon used in your typical hiking pants. It's maybe slightly more weather resistant (wind and water), a whole lot more durable, approx the same thermal insulation. There isn't a lot of stretch.

Think of dryskin as a bit like a North Face's Apex Pneumatic, or maybe a very thin windpro, or classic stretch ski pants that aren't waterproof: 4-way stretch, moderate wind and water resistance, slight insulation with a comfy fuzzy inside. On the legs it provides a HUGE comfort range. On the torso the moderate wind resistance can result in getting chilled. I purchase dryskin pants and a jacket something like 5 years ago. I still have the pants and I expect I will continue to use them until they are completely worn out. I sold the jacket after around a year of use.

I would describe WB-400 as armor plated PowerShield. I am not particularly fond of it, and haven't seen a situation when I would want to use it.

--Mark