I'm disappointed mithral and adamantine didn't carry over to the new armor types, and I would suggest that they do get included in a future update. As I see, there are two ways to do this:
1) Include mithral and adamantine as materials on top of existing new armor. This would mean that you can then have a Mountain Adamantine Plate, which is the same as a mountain plate, just made from adamantine instead of steel, giving the normal adamantine DR 3/- from heavy armor.
2) Have the new armor inherently have some of the properties of mithral and adamantine. They way I see this is that the "light" classes of armors (feycraft, spiritcraft and celestial) mimic mithral, meaning that feycraft gives -5% ASF and -1 SCP (skill check penalty), spiritcraft gives -10% ASF and -2 SCP, and celestial gives -15% ASF and -3 SCP. Similarly, the "heavy" armor line (magecraft, mountain and planeforged) mimics adamantine giving an additional DR 1/- for each step, meaning that a planeforged plate gives DR 3/-.
I'm sure you get the general idea, please consider this in a future update.
And one more thing: Please include a Hide Armor following the new armor progression for the Druid, since there are currently no random medium armor not made from metal.
Thanks!