Vs Combined Method? E+S from RFC 3156 6.2

[Marcus Brinkmann]

At Tue, 29 Apr 2008 14:14:45 +0200,
Bernhard Reiter wrote:
> Given the enhanced compatibility, why not do combined method whenever you can, 
> just getting the compatibility advantage?

Compatibility with what?  If every mail reader today supports MIME,
there is no advantage in not using it.  It would be more compatible to
have passwords with only uppercase characters, but luckily those
terminals have died out.  However, it is still advisable to restrict
passwords to 7 bit.  There are always such battles fought out.  A
GNOME terminal is 80 characters wide by default, for compatibility
with IBM punch cards, and I am actually annoyed if I have to read code
or documents that don't fit on punch cards.  But, luckily, that ain't
need to be so for everything.  Some things can move on.

So, the question is, are there significant MUAs that support only
combined mode?

Thanks,
Marcus