Really nice tutorial lots of good information and very well explained. However im not a Blender user so all the stuff about grouping and so forth etc. is probably very useful for those that use it. :D

However after watching the tutorial, I decided to check whether fresnel effect was in the PhysicalSurface node, so I downloaded your materials and they are very nice and really like the way you have organized them.

But i made a test scene to compare things to see the difference. So I took your car paint and tried to recreate it with the PhysicalSurface node to see if I could see a difference with the fresnel.

Here are the two images that I rendered one is using the cycle material and the other is using the PhysicalSurface node, which obviously got me wondering....

There is no difference in them as far as I can see.

However this is what the materials for each of them look like and don't get me wrong I know a lots of yours is because you can change color and material.

Cycles

PhysicalSurface

Im pretty sure all the materials could be made using 4 texture maps for each material when using the PhysicalSurface and don't misunderstand me, because im doing these comparisons and test because I want to learn, but it seems like a very complicated process with all these nodes and adding and mixing things together when using cycles, it seems like most of these things are build into the PhysicalSurface node already and more convenient to simply build on that.

What exactly is the benefit of using cycles? I could imagine that skin might be easier to make with cycles, but i really don't get why this cycle node is so fantastic and i really would like to know, I feel like im missing something with this node somewhere.