The short version, for anyone who has not been following closely.
Ask around and you will get a different answer every time, so here is the short version.
What it costs
There is a deadline involved, and missing it costs more than the difference. The exceptions matter more than the rule, and there are three of them.
Where to go from here
The exceptions matter more than the rule, and there are three of them. Most of the confusion comes from two terms that sound alike and mean different things.
What actually changed
The figures move about, but the direction has been the same for three years. Nobody is required to explain this to you, which is half the problem.
None of this is urgent, but it is worth an hour before the next renewal.