Well, as far as coming quickly to a consensus about your specific questions,
I haven't yet heard anyone argue that the idea that most environments
dont' change with nestsing (i.e. there's no double underlining) but that
bigger & smaller do have nested semantics. In other words, the common
sense interpretation rules.
It's obvious that the richtext spec will have to change, and possibly even
be decoupled from the main MIME document. But I think the changes can be
about 90% clarifications of the intent of the existing spec. The remaining
10% could make it eiethr more or less complex. I'll be pushing hard for
less complex. I personally wouldn't mind seeing things like subscripts and
superscripts disappear from richtext in the name of simplicity. -- NB