As someone who no longer does extreme fights or above (unless otherwise requested by friends), I think what most of everyone said here holds true: you need to try it to find out if you're actually capable, if you really aren't sure. If you're nervous about "failure," it might help to run it with friends, especially friends who are willing to teach or friends who are willing to learn with you.

Honestly, the hardest part of any of the higher ended fights is coordination; once you have a plan, and you put it into practice, it's a matter of repetition and practice until your success and/or raiders' fatigue sets in.
If you plan on pugging it, just go in there with the mindset that you'll do everything you can to help everyone succeed after you've settled yourself, and be patient with both the fight and the other players.