I called my MIL by her first name as she asked me to.
I don't think it matters what you call somebody as long as it is respectful and doesn't offend them. I don't subscribe to a theory that calling somebody by their Christian name makes a difference to the way they are treated. Most managerial problems tend to arise from the nature and attitudes of the people interacting with each other. A good manager will have less problems but if they are dealing with someone who doesn't take responsibility, has a chip on their shoulder or is work shy, then there is more likely to be a break down in working relations. It is the same with personal relationships, same faults, different circumstances.