Perhaps there was something wrong with your 2013 GS. I know there is a TSB to replace the non-laminated glass on the lower package GS with the laminated glass of the luxury package GS because of wind noise, mine is the luxury package. There is no wind noise, there is also very little road noise. Obviously the GS is a sportier car than the LS by design, so there is a level of connection to the road that the LS doesn't have.
I drove a 2010 LS460 back to back with a 2013 GS before I bought the GS, and while the LS is quieter no doubt as it is supposed to be, its not dramatically quieter, and the GS is certainly also very quiet.
I'm not quite sure why you went to the GS from the LS in the first place. Did you test drive the GS first? The LS is a much bigger car.