What should go into \textfont1

[karl@cs.umb.edu (Karl Berry)]

    This presents us with a problem: one scheme allows the LaTeX user to
    say \(\rm\bf\sigma\) and get a roman bold sigma, but the other
    produces better spacing.  Should a font standard aim to support
    logical markup, or beautiful typesetting?  The answer should be
    `both', which means that in practice the answer is probably
    `compromise'...
In principle, I would suggest that getting the right output is more
important than having logical markup.
People are willing to have to do ugly things to get the right output in
uncommon cases, but they are totally frustrated when a program cannot
produce the right output with any output.

I suspect that sufficiently clever macros can make almost any input form
work.