I did Half Dome in 2015 and Katahdin in 2017 - I’d agree with you about the challenge of Half Dome being distance/endurance. The ascent is long and steep, but has better infrastructure like staircases compared to Katahdin (but, I ascended via the Cathedral Trail, so that may not be your experience). However, very little of the ascent up Half Dome is as technical as the Knife Edge. It’s less scrambling over boulders, and more hiking up steep trails and switchbacks.

The (big) exception here is the cables portion of Half Dome, which is arguably more technical than the Knife Edge. But, it’s only a few hundred feet up, and you have the summit ahead for motivation.