In Canada we use them for permanent lighting in small areas such as crawl spaces. I have installed them protruded through a 1/2" knockout/w bushing in a regular octagon light box. The inspectors didn't seem to have a problem with it.
When something bumps them they just swing away. A cage, called for according to our 'under 7 foot' code rule would just get smashed, bulb and all, in a similar situation.
They should last as long as a regular fixture, but make sure your bulb wattage is low. As with any other fixture, I assume there is a max rating for them.
