This is a sideways suggestion -- but I use the Firefox plugin "It's All Text!" to send my text-areas to for editing -- all good markups,searching, etc.
Of course, this is user-dependent, and can't be easily rolled-out to visitors, if that is your intent.
However, I tend to get irritated by the limitations of in-browser editors, anyway. (The way SO captures my C-k during edits STILL catches me off-guard... [which means I don't edit everything in Emacs...])