I think your overall comparative analysis is good. And similarly, I have done lots of 10kft centuries as well as D-2 and D. There are a couple of key things to add:
- Many did Disaster with little to no rest period. I suspect that most of us ride centuries with plenty of break time (competitive GFs are the exception).
- The “Fireworks” portion about 3 1/2 hours into D is really hard (85% FTP with 10x 200% accelerations). 95% of users rated it 4 or 5 out of 5. Try it for yourself. Go out and do a really long, hard ride, then jump on your trainer and do Fireworks.