Well, I did a lot of renders last night and today with all kind of settings: GC, exponential tonemapping, HSV exponential tonemapping, GC in the shaders and so on and I read the whole wikipage about Gamma correction, both the english and the dutch (which have some contradiction BTW), and there are some pros and cons for using gamma correction:
Gamma correction makes better shadows and highlights and if you want realism in your render that's a good thing. Poserpro GC makes it very easy to use it.
But, I use a lot of dynamic hair and I have to change all the shaders because they are much too red and too bright for using GC. Because they use procedural shading,and GC only works on texturemaps you get very different results than without GC.
All the textures of clothes and props I bought are optimised for non-GC renders so I have change all the shaders before I get the same result with GC.
I have to change all the lightsets I made because they were not intended for using GC.
That's probably the reason why I preferred tonemapping over Gamma correction.
So yes, gamma correction is an improvement, but you'll  have a lot of work to do before your renders look the way you like it.
We have a VSS-prop for skins and there's also one for transmapped hair, it would be nice if I could have one for dynamic hair and clothing

best regards,

Bopper.

-How can you improve things when you don't make mistakes?