I've only been pulled over twice while carrying, once in Georgia and once in Indiana. Both times I informed the officer I was carrying...with two completely different responses.
Georgia. It was one of those nice, cool sunny days with the windows down blaring some good rock. At those times it's nearly impossible to NOT get a little lead footed. I happened to be going through a construction zone (without workers present) and was going the speed that would be considered acceptable outside of the construction. So before the officer even comes up I place my pistol on the dashboard (in holster), keep my hands at the 10 & 2, and mention it to him when he comes up. He asked if he could put it on the trunk of my car during the stop which, of course, I agreed to...never even asked me for my license but that's because it's not illegal to carry in your car in Georgia without a license (they consider your car an extension of your house). He comes back, hands me a ticket, and explains to me that since it was his chief that was running laser, he HAD to give me a ticket. But since I was so cooperative, he wanted me to request a court date and he'd do whatever he could to get it annulled. I show up to court a couple of months later and he made good on his promise; he made a $581 ticket disappear. Overall a positive experience.
Indiana...speed limit change that I did not see (went from 55-40 and I did not see it so I was pulled over for 57 in a 40). Same situation with the LEO. This time, he asked to see my license and I pulled it out (Georgia CCL...reciprocated in IN). He then asked me if I had an IN permit and I answered "No. Indiana reciprocates Georgia's permit." He gave me some specific instructions regarding the pistol until he secured it himself and went back to his car. He came back, gave me a speeding ticket, and put the pistol in the floorboard behind the driver seat, with the magazine detached and the chambered round out, and let me go. Not as positive since he still gave me a ticket, but he wasn't a complete jerk about it so it wasn't exactly negative.
I'll personally inform unless I'm in a state where it is not legal for me to carry