My base weight will be between 12-13 pounds. I've hiked the JMT before and I'm well aware of the elevation gain. Personally, I had no issues with the elevation, grade, etc on this trail. I was expecting it be a lot worse than what I experienced. I hike 16+ hours per day during the majority of my hikes, so the time on my feet is not an issue. As an ultraunner and speed hiker, I don't have the issues with foot placement, etc that a normal hiker would experience.
I speed hiked 298 miles of the Mountains to Sea Trail in under 7.5 days - averaging 38.8 miles per day. I found the MST to be more difficult than the JMT.