context matters
This isn't the only reason to oppose, just the one that's most obvious to me: I don't want to see a Registry of Houses Worth Robbing.
In that regard, knowing that guns are a) inherently valuable and b) useful in the commission of further crimes, if I were a burglar intent on an interesting score, I'd be interested in knowing which houses have gun-owning residents, for two reasons:
1) Hey, rob this one when it's nice and *empty*!
2) I bet most CCW permit holders (and "many" is an even safer bet) have more than one gun.
Anyone with a concealed carry permit almost certainly has a handgun, and (In Pennsylvania, outside large cities) probably at least one long-arm as well.
For anyone who says they'd not mind so much having their info published, consider a parallel question: Would you like to see a list published in grid format with checkmarks to show which householders have any *other* particular goods? (I know, CCW and gun ownership aren't the same, but I think they're close enough here.) Imagine finding yourself and your neighbors on a list for ...
Large-screen LCD TVs
Recent model laptops
Expensive, pawnable power tools
High-end stereo equipment
Jewels
Unlike commodity electronics, guns really are closer to jewels or (other) art objects, in that their value sticks or increases.
Also, how about a list of people with security systems?
timothy