Tweak, the other day I looked into it a little more, and decided the same thing for myself. I had read a pretty good review on them, but when I started searching around for more info, I found that they really don't help that much, they just save you from crushing the core.
Also, I learned that the Durons and Thunderbirds radiate heat from the core, to the outer edges of the chip, and into the heatsink, and a shim could hamper that.
So for now, no shims for AKDUDE.