Good post. I'd like to chime in that it's okay to take off the pack if it helps you get through a tough spot - I always carry a good length of paracord so I can have someone pull up my pack, or so the pack can be lowered safely.

A few more tips I can think of are:
- only move one hand or foot at a time
- it's safer to climb down while facing the rock rather than facing outwards; imagine climbing a ladder with a backpack and you can see what I mean