Does the ASP pulley dampen the harmonics that damage crankshafts? Are the two halves only connected by rubber or some sort of damping material?

Then again, I'm sure ASP probably says it does, I guess the only way to tell is to use it and see if something

 

Most have had good luck with the ASP pullies. Wether or not it's a true dampner is debatable.

 

I agree, and don't know how they call it something about fluid dynamics. I'm sure there's some articles around here about that, but you'll be safe simply running the ASP.