Validity, soundness, and formal vs. informal fallacies

Questions about whether two logical people can come to conflicting conclusions on a topic without committing a fallacy, how Greg, as a public figure, deals with criticism, and whether or not criticism gets to him.  

• Can two people come to conflicting conclusions on a topic while holding true to logic and reason without committing a fallacy?
• As a public figure, how do you deal with criticism, and does it get to you?