Do you guys use this option when rendering? i guess what am trying to say is if this should be used?
If you need it, yes 
On a more serious note: It is used if you render linear and save linear. this way you can force sampling to be gamma corrected (to prevent undersampling) and still save linear colors without baking in sRGB.
Regards,
Thorsten
what instinct said but also we crank the value to something like 3, so higher sampling is performed in darker area.
Yeah, I’ve tried this trick before and seems to work to a point… Gamma 3.0 is about the sweet spot.
Anything higher and the lack of contrast between pixels tends to work against sampler.
ok so just wanna make sure am using this correctly, right now were arent using linear workflow, but i like to have the option there when needed so my settings are as follows, 3dsmax gamma 2.2 input and output 1.0 vray gamma 2.2, dont effect background and dont affect colors is checked. should i check sub pixel mapping?