[A bunch of stuff, of which at least half of the truly technical
advances are already in XEmacs.]
Really the big technical difference is good support for non-Western,
non-Hanzi scripts (although I note GNU is still missing bidi support).
But what's really important in your list is lots of love from a large
developer population. Unfortunately, some of those developers are
people I am not comfortable working with (most importantly, RMS), and
I dislike working on GNU code (XEmacs code, Ben Wing's stuff
notwithstanding, is way easier for me to figure out than Emacs code at
least up to pre-22).
It's a shame we can't merge the GNU docs. And better Unicode support
is going to take some effort. But the other stuff you mention was
either pioneered by XEmacs, or not so hard to add.
The bottom line is that I'll have to take a look at NEWS, but in the
list of technology you present here there's nothing particularly
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