I once had the same plan and you can see some of the ideas it produced at
this page, but I think that it is far too late to catch up with (x)emacs. See e.g. the node I just wrote: Re: Learning Emacs
in reply to Favorite or most wanted text editor features?
I still feel it would be cool to have a perl interpreting editor, and I still think I have some pretty design thoughts, plus some real good features, but YATE (yet another text editor) just feels so wrong. For me XEmacs has almost all powers I could imagine - besides that I have to write the defuns in elsip ;-), for others vi(m) is really _it_. Yes and I even know people how feel content with nedit *grin*.
It's just some things missing like different highlighting (and maybe keybindings) in format strings or at other places - usually most of them come down to have several differents modes in one file at different positions, which is a relatively new requirement with PHP and HTMl mixed up (or JSPs or HEREDOCS or...). It will probably be more effective to get those features into existing architectures that starting a whole new editor project.
As for your regexp search: of course emacs can search for regexps, they're just plain ugly - uhm, I wanted to say: not of the elegant perlish style. And you can setup the levels of undo you'd like to have.
you begin bashing the string with a +42 regexp of confusion