"What is the back up if you miss the the 14.05?"
I agree, that's the key question. What will you do if something doesn't go according to plan?
"If I don't take that one, I will have to leave/arrive 2 hours earlier."
I understand that you really don't want to do that, but that's what I'd recommend. You certainly don't need to be at the Munich airport four hours early, but this gives you a cushion if something should go wrong and you get delayed, or if the airport formalities take longer than normal, or there's any other snag.
I'm fond of the aphorism, "At airports you can be either stressed or bored. Choose bored."
As Frank says, different people do this differently. One poster here was very angry that everyone recommended a conservative timing, and that he had lots of extra time wasted due to getting to the airport so early. Others would be much angrier at missing their plane. Having once almost missed a plane, I know how I would do it - but you have to do what you feel most comfortable with.