Took a gander through searches, and only found a couple offhand comments on this, so wanted to address it proper. In RC, a positive metagenic quality called Dermal Alteration has several iterations, depending on just how you wanna look. Two of them, Granite Shell and Rhino hide specifically state they are "not compatible with any worn armor." Additionally, Dermal Alteration is "incompatible with any other natural or artificial skin modifications."

To me, "not compatible" and "incompatible" mean you simply cannot have both. That said, I have questions...

1 - If you take Dermal Alteration as a troll, does it *replace* your natural Dermal Deposits? Or can you simply not take the quality at all because you're a troll?

2 - If you take Granite Shell or Rhino Hide, can you never wear armor?

Nitpick: 3/3 Hardened armor seems to only be effective against an average human(ish) punching you. Anything more and you don't just shrug it off, and actually have to resist the damage. But this was already milled over in regards to drakes and their nigh-useless 4/4 hardened armor, so I suppose bringing it up again is rather pointless.

Given that both of those skin alterations are described as "count[ing] for Armor and Encumbrance", I think the 'not compatible' term means that, unlike things like PPP system and Dermal Plating, they do add into the calculation for Encumbrance with other forms of armour. As you suggest, it would be pretty silly to take one of these Qualities if they preclude the use of any other form of armour.

It would be silly anyway, as they don't offer any meaningfull protection and cost points and your own frigging skin weights you down . .

I guess I'm just on a wording nitpick today. They use "not cumulative" with armor in other areas, but here specifically say incompatible. Makes it sound like you simply can't use armor with Granite Shell.

And turns our Rhino Hide says "not cumulative", rather than "not compatible" with armor, so strike that from my original post.

Wow. And here I was sitting and thinking that Drakes had the worst deal out there (aside from Force 1 spirits).

Well, not the worst, but still pretty meh . .

Aside from the a fore mentioned 3/3 and Force 1 spirits, what else has 4 or less Hardened Armor?

Nothing much, maybe one or two weak critters.
I think the shamblers shell counts as hardened armor.
And that gets stronger over time. So i think it's weak
in the beginning, but i am not sure about that at all.

1. I would say it replaces your natural dermal deposits (at least that is how I would rule it in my game)

2. My guess is that granite skin is malformed for standard armour and as such it just doesn't fit. Some clothing would also not fit properly. It is hard to put on a shirt when you have spiky bumps all over you.

It worked for Spike.

SURGE also applies to NPCs and critters. So as a player you may not view it worth as much, but if you are fighting say a pack of wolves with rhino skin or granite skin then it could cut down on the fatalities from grenades. SURGE gives some cool powers for the creatures in running wild. Granite skin does prevent damage from minor nuisances such as insect stings.

To throw a hand grenade and run what happens if you combine it with a Magic 6 adept with 6 points of mystic armor. If says it magically toughens your skin do you get 9 hardened points of armor?

No one knows how hardened armor stacks with normal armor.
Or how Mystic (adept) Armor stacks with Hardened Armor.

If the Adept does not get Hardened Armor from somewhere, mystical armor does specifically not count as hardened armor.

I always took "incompatible" to mean that the armor bonus provided by Granite Shell and Rhino Hide didn't stack with worn armor at all. Your armor would just be the higher of the two values. So you could take Granite Shell and still wear worn armor, but if you were ever caught with your pants down (so to speak), you'd at least gain the protective bonus from Granite Shell.

Force 2 spirit.

Originally I had been counting that as "tied" with drakes, so I was really looking for something with less, the only reason to ask for "what else has 4" is anything that isn't a force 2 spirit or a drake.