I built up from your shader. The parts you and I added do not attempt to deal with gamma. The rest of it (the skin) does. I can turn the gamma node back to 2.2 but it doesn't magically alter the new additions just because I want it to. I have to anti-GC the metal color and the two paint colors, anti-GC the reflection, combine them all upstream of the final gamma correction. You had made the insertions after the final gamma and so that was where I picked up. For the time being, I turned off the shader GC and enabled render GC, thus all that was automatic. But to finish the job, one would expect the shader GC to work on the finished 4-material shader, not just the skin part.

Part of the reason your metal didn't look right was lack of GC. Mine is looking right because of GC - nothing else about it is different. 

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)