Do I earn less experience or items if I have a follower?
In Act 1 of Diablo 3, I encounter a warrior who is later revealed to be a Templar. After I help him find his weapons, he wants to join my party. The only condition is that if I encounter the tomes of his order, I give them to him.
What are the benefits of letting the Templar join my party? Are their any drawbacks? Does having a follower increase minion difficulty like when you're playing with other people?