I'm an LII. I held out for quite a bit on ILE, not wanting to be a rational type, but everything else checks out better as the former.
I am wondering, though, do members of a given temperament occasionally 'jolt' into their opposite?
It would make sense with the Base/Creative functions, and otherwise temperaments only make sense for particularly extreme individuals.
Yeah there is some sort of self-dualization process that appears to kick in with age. From personal observations I'd say it starts in late teens and fully unravels by late 30s. You go around acting normally out of your ego and then *whoosh* and the super-id block starts acting up. The first attempts of it to 'unravel' come in very strong and rather unrefined, but it gets better with age especially if you spend time with your dual/activity then they can give you some better refined super-id information.
For LIIs I know it can manifest as episodes of extreme emotionalism, feeling like nobody loves you, nobody appreciates you, seeking affirmation from others, becoming hyper-sensitive to approval of other people, suddenly realizing that you don't want to die alone. That's the DS Fe kicking in.
Some individuals experience this more often than others. There are cases where the individual rather frequently refers to his or her super-id block especially the mobilizing function. If you're observant enough of other people, you can pick this up because super-id elements don't act with very good refinement. One possible reason can be that they have found themselves in environment where their ego is not appreciated, so then they attempt to 'escape' and start flipping into their opposite personality.
A somewhat related article: http://www.socionics.us/practice/ego.shtml