I'm going to wade in here as I've had some moments where something like this has put my back up. I've heard variations on "You have a great camera" a few hundred times now.
Initially I got my back up and took offence, but I realized something; often the people asking this aren't looking to rib you, they are just trying to break the ice because they want to talk to you. Sure, maybe they are gear nuts but often they are hobbyists, amateurs or enthusiasts who admire what you are doing. Often they are both admirers and gear nuts rolled into one. And that's a good thing.
I have a playful way of handling that question now while I'm working; I'll feign being hurt a little and say something like "You know, I'd like to think I'm pretty good at what I do... but my ego is quite fragile and you just broke my heart"... followed by a laugh and the assertion that I do love the camera I'm using, but it takes some time to learn to use it well. Sure, if they are trying to engage you in a lengthy chat when you have work to do it can be a small hindrance, but then a polite "I have some things I have to shoot, but if you're around for a bit I'll free up later to chat" works really well.
Form there I might find out that the person teasing me has a Canon Rebel/an old Pentax K-1000/just bought their fist P&S/is thinking about buying their first full framer/iPhone 5S. And you know what? Those are all great cameras. And the fact that that person loves cameras and photography is keeping us employed. Really.
Now, not to say all folk that ask this are benevolent, but most are. As for the occasional jerk, you can usually tell who they are after a few back and forths... I've had a few here and there. I usually tease them too... and then go back to work.