Great article. Good to see some research into this oft-argued topic (particularly the sp_ prefix!).
Following on from a few questions back, I'm still not sure if the answer was yes to multiple tables in the same database within different schemas, or if the answer was yes to same table within multiple databases. If the former, then do what works for you. If the latter then the next question would be...
You have databases A & B. Are they completely separate - Does A access B's tables or vice-versa? If so then you need three part naming, otherwise stick with two part naming.
Somewhere on this site there's a "worst practices" series of articles. One of them was having objects not owned by dbo. Direct flames in that article's forum if you don't agree