I don't know about "G" being "government". What it does mean is decoker only, so there's no "safe" postion. You use the lever on the slide the same way you use the decock lever on a Sig, to safely lower the hammer. The idea is that there's no way the gun will be in any mode but ready to fire as the decocker springs back to the "fire" position. It also eliminates the unlikely chance that you could knock the safety into "safe" when operating the slide during a stoppage, reloading, etc. It's a good version to have available, it just depends on if you want a "safe" postion or not.
I think as a Glock owner, the G would be a good choice for you, since you're not used to a manual safety already. There's nothing different in the way you deploy either gun.
Cost isn't any different than an FS of the same condtion that I've noticed.
Really good choice for your IMO.