I wish he'd left the security advice out. The whole post was excellent, but all the useful points will now be overshadowed by the armchair quarterbacking about security by people who mostly don't understand that ALL security is a compromise, and it is as important to understand and make deliberate decisions about your security as it is to try to make a secure system in the first place.
I'm glad he put the security notes in. It is so hard to get true facts about how things are actually done.
He keeps many comments at a high level (security/convenience) and refers to a few non-Dropbox examples.