Doing armed security details in uniform and working armed in a few EP(executive protection) posts, I can honestly say having a OC sidearm can deter some criminals.
In the mid 2000s, I worked as a security officer for a hotel property in a high crime, high incident rate area. I wore my Ruger GPNY .38spl on duty. Several times I saw a few vehicles repeatedly "case" the hotel property, see me, then drive off.
One important point I'd make about armed/uniform carry is to wear a duty uniform that clearly identifys you front & back. This can prevent mishaps or misunderstandings. Being clearly identified can help protect you. Using the reflective type badges & patches avoid problems in low light.
It's important to remember that some LE officers may not know you have a concealed license or can carry OC. I've talked to a few patrol officers in my area who had little or no knowledge of the regulations/policy of the state's Div of Licensing. For the record, the state where I live had in-service training for LE but cut the program to save $$$.