The biggest problem I see with C3 is timing. In many personal defense scenarios having a loaded gun ready might not be fast enough to matter depending on circumstance. C3 for a personal defense situation off duty isn't much better then no gun at all from that perspective.
BUT, comma, training two different scenarios also poses a risk. It is part of why a "carry rotation" isn't the best practice for CCW,because different guns behave differently depending on their setups. The OP could carry C1 off duty/C3 on,but then he'd have to define when to draw and when to rack slide as part of the draw. He'd also have to change his admin handling habits - and it would be far too easy for the OP to load his Beretta at work C1 by accident because that's what he does with his Beretta at home or carry C3 by mistake off duty.
It's my understanding an admin handling fuckup like that would be punished disproportionately severely ; so this isn't a concern to dismiss.