The one bad thing about IC D is it will scratch the surface of the CPU / GPU. That is by design. So if you have any desire to potentially sell your CPU or GPU 2nd hand, then you might want to think twice about using IC D.
Actually for the GPU it should be fine 'cause most people do not replace the thermal paste on a GPU unless they really need to... and unlike the CPU, the heatsink will already be attached.
interesting, but i dislike the fact it scratches the surface of the cpu.