That would require a lot more escaping when you aren't writing markup (as using parenthesis in regular writing is so common).

Yep, my thoughts exactly.

If you call it lispy it's gotta use parens.

The curlies immediately suggest some broken json or perl hash.

I can see the lispy spirit in applying the car to the cdr, and I like it!

One first bug report (or feature removal request):

  makes it to the output, but is replaced with the U+00A0 character in the input textarea.

{p like   so}

What's the concern with a real lisp syntax?

I for one like it!

It's pretty easy to switch the delimiters. I plan to add it to a roleplay site first because they use parens much more than angle brackets. You can see the old version here, but it's a line by line parser http://rp.eliteskills.com/editing.php . They're using it every day.