In reply to Mark Haward:
My experience is a bit out of date as it was from maybe 6 or 7 years ago.
> People often bunch up here and form a queue, climbing right behind each other.
You definitely want to be careful on that section, when we were there there was a group of a dozen or so climbers in the middle with all their ropes criss-crossed and stuck all yelling at each other and (as far as I can recollect) in the time we climbed it, none of them managed to move at all. There were guides with clients who were barely conscious and posing a serious risk to other people on the slope. We had semi-conscious clients repeatedly trying to pull us off the mountain by treating our ropes as situ ropes, no matter how many times their guides shouted at them telling them not to do so. I had one guy repeatedly sticking an elbow into my chest and trying to shove me off down the slope (I have literally no idea why) and he only desisted when I threatened him with my ice axe (apparently some instinct for self-preservation remained activated).
In short, the combination of guides trying to make money and incapable rich people wanting to get to the top creates something of a perfect storm for competent people climbing under their own steam (I imagine it is similar but much worse on Everest). On the steeper section, steer clear of everyone else if you possibly can.
When you are planning start times, clothing, etc. Remember that you will be in a queue of hundreds of people going at the speed of the slowest person for significant parts (but by no means all) of the route.