you will see a VERY big difference in the color viewed from behind the glass.
for example try making a simple box, put the vray materail glass on the box, set the environment color to sky blue and render, use exponential and hsv color mapping and render. I have noticed that when you use the vray material as glass (having refract all the way to white) and adding a very slight reflection (its glass anyway) and using the exponential or HSV color mapping algorithm, the background environmnet color gets affected a LOT.
