That's a big problem I have with GMing, deciding where to draw the line between friendship/friendliness and business. I find myself being much more lax with friends, letting them do things that I might not be particularly fond of and wouldn't let a new person do. Though I've also noticed I'm never sure if I'm being to strict, or controlling, with all my players. I don't want to be a pain in the ass GM who is super strict, but I don't want to allow the players to derail the rp by doing some crazy idea. Whenever I GM I find myself conflicted and unsure how I should act. 

*coughs* well I'm just rambling and have probably deviated from the original point of this topic. So... yeah