I definitely have, the only way to figure out if you like something is to try it a couple of times. Fear, or just being out of my comfort zone as you said, shouldn't be the inhibitor in my mind.
Where is the most uncomfortable place to have sex?
Too long? Granted I want it every day, so anything over a couple of weeks and I'll say too long. It's definitely been more than a couple of weeks.(more specific, over a month)