I described my experiences in a sibling comment. But regarding the discomfort of long hours, I have been using it comfortably for 7-12 hours a day for six days now.

I had to go to the double strap to distribute the weight evenly.

You also rethink where you want to be. My desk is still great, but a tilted back chair with a keyboard/pad on my lap is better for longer hours. That is where I am now!