Hey Geoff, I had remembered reading your article when it was first published but I had never considered bougainvillea for my own garden so I mainly just looked a the pictures (which are great) and read the article without studying it. However, a good friend of mine just went to S.F. and fell in love with the bougainvilleas he saw there and is now considering adding one to his yard and he wanted to know what I thought about them.
After re-reading your article I think I can give him a pretty accurate recommendation. But before I do, I thought I'd run it by you. We're in Zone 9a which sounds like it might be just outside of the hardiness zone of 9b mentioned in your article. But we do have a very mediteranean climate (hot, dry summers / cold, rainy winters). I think that with some TLC in the winter when it gets close to freezing and regular watering in the summer he could probably grow them successfully but if he chooses to go forward he should probably expect occassional die back.