For the technical writing, I actually wrote a comment here somewhere about that in another post; I'll have to dig it up and turn it into a blog post at some point. But I called it a "fast Swiss army knife for text." Its "open file by name via fuzzy searching" command lets you enter multiple files, its multi-file search window lets you save file filters with meaningful names (and you can save grep patterns the same way, and in BBEdit 13 there's even a "Pattern Playground" that lets you nondestructively test out complex regexes on your current document). Projects get their own persistent scratchpads and Unix worksheets. And, a bit relevant to an Emacs thread, BBEdit has a bit of Emacs-ish keybinding support over and what Mac editors normally do, although it's decidedly not an Emacs emulation layer.
Yeah, either that or they are procrastinating on some quirk deep in their engine they should rewrite already.
Please produce that post. Also, why not developing in BBEdit?