Joe replied:
My opinion: add exactly one more element, and then stop. Any new
formatting characteristics should be added as attributes on that
element. (This would have to be a new element because all of
the existing formatting elements are special-purpose.)
This is what the TEI does. <hi> is explicitly there to describe
material which is highlighted in some way in the source document, but
where the reason for it is unknown or non-relevant. Like the current
vogue for isolated words in large italic in display adverts, what one
colleague called "non-specific elefontiasis" :-)
///Peter