This subject has been discussed so many times on so many forums, it's scary.
Here's my opinion on it and strictly my opinion. If you aren't carrying with one in the chamber, you may as well not carry at all. Keep in mind, in a defensive scenario, YOU are the target. The bad guy has already sized you up, he's figured out how he wants to approach you, and is on the way to do the deed before you even know there is a situation. At the moment he is upon you, drawing, loading, and engaging your target is not an option. That single split second spent attempting (again, attempting) to load a round, is an additional split second your attacker has to shoot you, stick a knife in you, or just get in that first blow that takes you out of the fight. Remember," HE" already has a plan, you are at a disadvantage because you have to react to a plan you know nothing about.
If you're that uncomfortable carrying with one in the chamber, carry a revolver with an empty chamber under the hammer. At least when you have to pull the trigger, there's a round in there to go boom, albeit you're starting one round short from jump. Just some things to consider.
Good Luck and good shooting.
PS... Another lesson to be learned here, DON"T rob a store.
PSS... Also makes you rethink appendix carry ;(