Certainly looks promising. I like the overall idea, though like
others I have reservations about flag days and also to a lesser extent
about dual syntax.
I can live with a dual syntax, but it would be nice to avoid it. But
if it helps speed this process, whether because of technical merits or
as a pragmatic political compromise, then so be it.
Flag days worry me from a deployment point of view, though I can't see
an obvious alternative if the concensus is that it's important to
reject before DATA...
-roy