I was also looking between the two but unlike you, I did not have the option as the ADs I visited did not have the GV. I did the next best ting which was to buy the GMT IIc as it was a useful complication, has a date magnified ( I am getting long-sighted) and as new as it could get from Rolex in terms of technology and design.
Bottom-line : Go for what suits you and hat you like best! Good luck deciding.