Paul understands himself as a steward of the mysteries of the God. It is required of a steward that he be found faithful. To that end Paul preaches the same message in every church (1 Cor. 4:17). It's not his message, it belongs to someone else.
"God will judge, so I don't need to." This is such a key idea for maintaining a clear conscience.
His strategy is to make this church ashamed by recounting his struggle and pain (often at their hands, I'm sure). I'm fascinated that Paul is unwilling to let some things slide. Their treatment of him is not an OK think to let slide. He confronts their disrespect, but he does it in relationship -- I am your father in the Lord (1 Cor. 4:15). When should I defend myself and when should I let things slide?
Paul sees imitation, even over a distance, as his best means of discipling the church. He even sent Timothy to remind them to imitate him. We see it again in 1 Cor. 11:1.