Yes, external is much more comfortable - by a long shot. (No pun intended.) However, will your company allow you to wear the external one? Wearing a uniform without a vest can be very dangerous. You may be unarmed at this site, but you're still a target if you're in uniform. What color is your uniform? A lot of the dark ones look an awful lot like law enforcement which can make you even a bigger target. At least G4S doesn't look as much like LEOs (although they could be mistaken for Florida state troopers).
There are two types of people in this world: Those who can extrapolate from incomplete data.