Are you using the 3ds Max frame buffer, or the V-Ray one? What file format are you saving the image to?
In any case, there is the possibility that V-Ray will clamp the result of any material evaluation to be always non-negative (negative material colors typically indicate an error in the shader and in a normal scene lead to all sorts of issues, especially with GI).
If I am not too confused both should have been tested.
I want to save as full-float exr.
Not everything is clamped.
Here is a link to my great test-scene for the point-pass-clamping. http://www.3dwolf.de/stuff/VraySampleInfoTexPoint\_MtlPass\_noRE.max
Also notice that it seems to work in the medit-preview on the 3rd material which is the vray-mat. But as I am not really a heavy VRay-user there might be some simple mistakes an not-knowing-errors.
I would have no problem with render elements if the max-exr-configuration would work reliable in backburnerrendering. It seems to ignore or mess up the colordepth and RE-settings on different jobs. But I guess that is a hole different issue.