Even in *scratch*, where font-locking overrode those, I think?

The issue still remains -- if you do this in emacs -nw:

(format "%c5" 128)
"€5"

And cut and paste that do a different Emacs, you get the string

"\x805"
=> "ࠅ"

But...  we've had this format for half a decade now, and this doesn't
really seem to be a problem in practice, so while the format is somewhat
ambiguous, I tend to think that introducing a new syntax just to fix it
isn't worth it.  Especially a syntax like \x{80}, which was one of the
suggestions -- the idea, after all, is to make display prettier and more
readable.

Any further opinions?

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no