I disagree Gaidin. Both are solid particles suspended in silicone grease. MX3 is carbon, as5 has silver involved. I don't doubt there are other solids suspended as well, people occasionally try diamond. Since the solids are suspended in silicone, I consider them silicone based
Since AS5 is particles in silicone, and so is MX2, a mix of them is just a lot of different particles in silicone grease. It probably performs roughly as the weighted average of the two. Silicone grease by itself does a reasonable job.
The air bubbles from the even spread are interesting, but I'm not convinced they'd persist when repeatedly heated and cooled under pressure